89163f93c6
163 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Kees Cook
|
1d2252fab9 |
kasan: unset panic_on_warn before calling panic()
As done in the full WARN() handler, panic_on_warn needs to be cleared before calling panic() to avoid recursive panics. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Elena Petrova <lenaptr@google.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Link: http://lkml.kernel.org/r/20200227193516.32566-6-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
Alexander Potapenko
|
505a0ef15f |
kasan: stackdepot: move filter_irq_stacks() to stackdepot.c
filter_irq_stacks() can be used by other tools (e.g. KMSAN), so it needs to be moved to a common location. lib/stackdepot.c seems a good place, as filter_irq_stacks() is usually applied to the output of stack_trace_save(). This patch has been previously mailed as part of KMSAN RFC patch series. [glider@google.co: nds32: linker script: add SOFTIRQENTRY_TEXT\ Link: http://lkml.kernel.org/r/20200311121002.241430-1-glider@google.com [glider@google.com: add IRQENTRY_TEXT and SOFTIRQENTRY_TEXT to linker script] Link: http://lkml.kernel.org/r/20200311121124.243352-1-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Marco Elver <elver@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Link: http://lkml.kernel.org/r/20200220141916.55455-3-glider@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
Walter Wu
|
8cceeff48f |
kasan: detect negative size in memory operation function
Patch series "fix the missing underflow in memory operation function", v4. The patchset helps to produce a KASAN report when size is negative in memory operation functions. It is helpful for programmer to solve an undefined behavior issue. Patch 1 based on Dmitry's review and suggestion, patch 2 is a test in order to verify the patch 1. [1]https://bugzilla.kernel.org/show_bug.cgi?id=199341 [2]https://lore.kernel.org/linux-arm-kernel/20190927034338.15813-1-walter-zh.wu@mediatek.com/ This patch (of 2): KASAN missed detecting size is a negative number in memset(), memcpy(), and memmove(), it will cause out-of-bounds bug. So needs to be detected by KASAN. If size is a negative number, then it has a reason to be defined as out-of-bounds bug type. Casting negative numbers to size_t would indeed turn up as a large size_t and its value will be larger than ULONG_MAX/2, so that this can qualify as out-of-bounds. KASAN report is shown below: BUG: KASAN: out-of-bounds in kmalloc_memmove_invalid_size+0x70/0xa0 Read of size 18446744073709551608 at addr ffffff8069660904 by task cat/72 CPU: 2 PID: 72 Comm: cat Not tainted 5.4.0-rc1-next-20191004ajb-00001-gdb8af2f372b2-dirty #1 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x288 show_stack+0x14/0x20 dump_stack+0x10c/0x164 print_address_description.isra.9+0x68/0x378 __kasan_report+0x164/0x1a0 kasan_report+0xc/0x18 check_memory_region+0x174/0x1d0 memmove+0x34/0x88 kmalloc_memmove_invalid_size+0x70/0xa0 [1] https://bugzilla.kernel.org/show_bug.cgi?id=199341 [cai@lca.pw: fix -Wdeclaration-after-statement warn] Link: http://lkml.kernel.org/r/1583509030-27939-1-git-send-email-cai@lca.pw [peterz@infradead.org: fix objtool warning] Link: http://lkml.kernel.org/r/20200305095436.GV2596@hirez.programming.kicks-ass.net Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Suggested-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com> Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Link: http://lkml.kernel.org/r/20191112065302.7015-1-walter-zh.wu@mediatek.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
Linus Torvalds
|
a1084542a8 |
RISC-V Patches for the 5.6 Merge Window, Part 1
This tag contains a handful of patches that I'd like to target for this merge
window:
* Support for kasan.
* 32-bit physical addresses on rv32i-based systems.
* Support for CONFIG_DEBUG_VIRTUAL
* DT entry for the FU540 GPIO controller, which has recently had a device
driver merged.
These boot a buildroot-based system on QEMU's virt board for me.
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Merge tag 'riscv-for-linus-5.6-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V updates from Palmer Dabbelt:
"This contains a handful of patches for this merge window:
- Support for kasan
- 32-bit physical addresses on rv32i-based systems
- Support for CONFIG_DEBUG_VIRTUAL
- DT entry for the FU540 GPIO controller, which has recently had a
device driver merged
These boot a buildroot-based system on QEMU's virt board for me"
* tag 'riscv-for-linus-5.6-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
riscv: dts: Add DT support for SiFive FU540 GPIO driver
riscv: mm: add support for CONFIG_DEBUG_VIRTUAL
riscv: keep 32-bit kernel to 32-bit phys_addr_t
kasan: Add riscv to KASAN documentation.
riscv: Add KASAN support
kasan: No KASAN's memmove check if archs don't have it.
|
||
Nick Hu
|
57ee58e393
|
kasan: No KASAN's memmove check if archs don't have it.
If archs don't have memmove then the C implementation from lib/string.c is used, and then it's instrumented by compiler. So there is no need to add KASAN's memmove to manual checks. Signed-off-by: Nick Hu <nickhu@andestech.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> |
||
Jann Horn
|
2f004eea0f |
x86/kasan: Print original address on #GP
Make #GP exceptions caused by out-of-bounds KASAN shadow accesses easier
to understand by computing the address of the original access and
printing that. More details are in the comments in the patch.
This turns an error like this:
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault, probably for non-canonical address
0xe017577ddf75b7dd: 0000 [#1] PREEMPT SMP KASAN PTI
into this:
general protection fault, probably for non-canonical address
0xe017577ddf75b7dd: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: maybe wild-memory-access in range
[0x00badbeefbadbee8-0x00badbeefbadbeef]
The hook is placed in architecture-independent code, but is currently
only wired up to the X86 exception handler because I'm not sufficiently
familiar with the address space layout and exception handling mechanisms
on other architectures.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: kasan-dev@googlegroups.com
Cc: linux-mm <linux-mm@kvack.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191218231150.12139-4-jannh@google.com
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Daniel Axtens
|
e218f1ca39 |
kasan: use apply_to_existing_page_range() for releasing vmalloc shadow
kasan_release_vmalloc uses apply_to_page_range to release vmalloc
shadow. Unfortunately, apply_to_page_range can allocate memory to fill
in page table entries, which is not what we want.
Also, kasan_release_vmalloc is called under free_vmap_area_lock, so if
apply_to_page_range does allocate memory, we get a sleep in atomic bug:
BUG: sleeping function called from invalid context at mm/page_alloc.c:4681
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 15087, name:
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x199/0x216 lib/dump_stack.c:118
___might_sleep.cold.97+0x1f5/0x238 kernel/sched/core.c:6800
__might_sleep+0x95/0x190 kernel/sched/core.c:6753
prepare_alloc_pages mm/page_alloc.c:4681 [inline]
__alloc_pages_nodemask+0x3cd/0x890 mm/page_alloc.c:4730
alloc_pages_current+0x10c/0x210 mm/mempolicy.c:2211
alloc_pages include/linux/gfp.h:532 [inline]
__get_free_pages+0xc/0x40 mm/page_alloc.c:4786
__pte_alloc_one_kernel include/asm-generic/pgalloc.h:21 [inline]
pte_alloc_one_kernel include/asm-generic/pgalloc.h:33 [inline]
__pte_alloc_kernel+0x1d/0x200 mm/memory.c:459
apply_to_pte_range mm/memory.c:2031 [inline]
apply_to_pmd_range mm/memory.c:2068 [inline]
apply_to_pud_range mm/memory.c:2088 [inline]
apply_to_p4d_range mm/memory.c:2108 [inline]
apply_to_page_range+0x77d/0xa00 mm/memory.c:2133
kasan_release_vmalloc+0xa7/0xc0 mm/kasan/common.c:970
__purge_vmap_area_lazy+0xcbb/0x1f30 mm/vmalloc.c:1313
try_purge_vmap_area_lazy mm/vmalloc.c:1332 [inline]
free_vmap_area_noflush+0x2ca/0x390 mm/vmalloc.c:1368
free_unmap_vmap_area mm/vmalloc.c:1381 [inline]
remove_vm_area+0x1cc/0x230 mm/vmalloc.c:2209
vm_remove_mappings mm/vmalloc.c:2236 [inline]
__vunmap+0x223/0xa20 mm/vmalloc.c:2299
__vfree+0x3f/0xd0 mm/vmalloc.c:2356
__vmalloc_area_node mm/vmalloc.c:2507 [inline]
__vmalloc_node_range+0x5d5/0x810 mm/vmalloc.c:2547
__vmalloc_node mm/vmalloc.c:2607 [inline]
__vmalloc_node_flags mm/vmalloc.c:2621 [inline]
vzalloc+0x6f/0x80 mm/vmalloc.c:2666
alloc_one_pg_vec_page net/packet/af_packet.c:4233 [inline]
alloc_pg_vec net/packet/af_packet.c:4258 [inline]
packet_set_ring+0xbc0/0x1b50 net/packet/af_packet.c:4342
packet_setsockopt+0xed7/0x2d90 net/packet/af_packet.c:3695
__sys_setsockopt+0x29b/0x4d0 net/socket.c:2117
__do_sys_setsockopt net/socket.c:2133 [inline]
__se_sys_setsockopt net/socket.c:2130 [inline]
__x64_sys_setsockopt+0xbe/0x150 net/socket.c:2130
do_syscall_64+0xfa/0x780 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Switch to using the apply_to_existing_page_range() helper instead, which
won't allocate memory.
[akpm@linux-foundation.org: s/apply_to_existing_pages/apply_to_existing_page_range/]
Link: http://lkml.kernel.org/r/20191205140407.1874-2-dja@axtens.net
Fixes:
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Andrey Ryabinin
|
d98c9e83b5 |
kasan: fix crashes on access to memory mapped by vm_map_ram()
With CONFIG_KASAN_VMALLOC=y any use of memory obtained via vm_map_ram()
will crash because there is no shadow backing that memory.
Instead of sprinkling additional kasan_populate_vmalloc() calls all over
the vmalloc code, move it into alloc_vmap_area(). This will fix
vm_map_ram() and simplify the code a bit.
[aryabinin@virtuozzo.com: v2]
Link: http://lkml.kernel.org/r/20191205095942.1761-1-aryabinin@virtuozzo.comLink: http://lkml.kernel.org/r/20191204204534.32202-1-aryabinin@virtuozzo.com
Fixes:
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zhong jiang
|
2e7d31704c |
mm/kasan/common.c: fix compile error
I hit the following compile error in arch/x86/
mm/kasan/common.c: In function kasan_populate_vmalloc:
mm/kasan/common.c:797:2: error: implicit declaration of function flush_cache_vmap; did you mean flush_rcu_work? [-Werror=implicit-function-declaration]
flush_cache_vmap(shadow_start, shadow_end);
^~~~~~~~~~~~~~~~
flush_rcu_work
cc1: some warnings being treated as errors
Link: http://lkml.kernel.org/r/1575363013-43761-1-git-send-email-zhongjiang@huawei.com
Fixes:
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Daniel Axtens
|
3c5c3cfb9e |
kasan: support backing vmalloc space with real shadow memory
Patch series "kasan: support backing vmalloc space with real shadow
memory", v11.
Currently, vmalloc space is backed by the early shadow page. This means
that kasan is incompatible with VMAP_STACK.
This series provides a mechanism to back vmalloc space with real,
dynamically allocated memory. I have only wired up x86, because that's
the only currently supported arch I can work with easily, but it's very
easy to wire up other architectures, and it appears that there is some
work-in-progress code to do this on arm64 and s390.
This has been discussed before in the context of VMAP_STACK:
- https://bugzilla.kernel.org/show_bug.cgi?id=202009
- https://lkml.org/lkml/2018/7/22/198
- https://lkml.org/lkml/2019/7/19/822
In terms of implementation details:
Most mappings in vmalloc space are small, requiring less than a full
page of shadow space. Allocating a full shadow page per mapping would
therefore be wasteful. Furthermore, to ensure that different mappings
use different shadow pages, mappings would have to be aligned to
KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE.
Instead, share backing space across multiple mappings. Allocate a
backing page when a mapping in vmalloc space uses a particular page of
the shadow region. This page can be shared by other vmalloc mappings
later on.
We hook in to the vmap infrastructure to lazily clean up unused shadow
memory.
Testing with test_vmalloc.sh on an x86 VM with 2 vCPUs shows that:
- Turning on KASAN, inline instrumentation, without vmalloc, introuduces
a 4.1x-4.2x slowdown in vmalloc operations.
- Turning this on introduces the following slowdowns over KASAN:
* ~1.76x slower single-threaded (test_vmalloc.sh performance)
* ~2.18x slower when both cpus are performing operations
simultaneously (test_vmalloc.sh sequential_test_order=1)
This is unfortunate but given that this is a debug feature only, not the
end of the world. The benchmarks are also a stress-test for the vmalloc
subsystem: they're not indicative of an overall 2x slowdown!
This patch (of 4):
Hook into vmalloc and vmap, and dynamically allocate real shadow memory
to back the mappings.
Most mappings in vmalloc space are small, requiring less than a full
page of shadow space. Allocating a full shadow page per mapping would
therefore be wasteful. Furthermore, to ensure that different mappings
use different shadow pages, mappings would have to be aligned to
KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE.
Instead, share backing space across multiple mappings. Allocate a
backing page when a mapping in vmalloc space uses a particular page of
the shadow region. This page can be shared by other vmalloc mappings
later on.
We hook in to the vmap infrastructure to lazily clean up unused shadow
memory.
To avoid the difficulties around swapping mappings around, this code
expects that the part of the shadow region that covers the vmalloc space
will not be covered by the early shadow page, but will be left unmapped.
This will require changes in arch-specific code.
This allows KASAN with VMAP_STACK, and may be helpful for architectures
that do not have a separate module space (e.g. powerpc64, which I am
currently working on). It also allows relaxing the module alignment
back to PAGE_SIZE.
Testing with test_vmalloc.sh on an x86 VM with 2 vCPUs shows that:
- Turning on KASAN, inline instrumentation, without vmalloc, introuduces
a 4.1x-4.2x slowdown in vmalloc operations.
- Turning this on introduces the following slowdowns over KASAN:
* ~1.76x slower single-threaded (test_vmalloc.sh performance)
* ~2.18x slower when both cpus are performing operations
simultaneously (test_vmalloc.sh sequential_test_order=3D1)
This is unfortunate but given that this is a debug feature only, not the
end of the world.
The full benchmark results are:
Performance
No KASAN KASAN original x baseline KASAN vmalloc x baseline x KASAN
fix_size_alloc_test 662004 11404956 17.23 19144610 28.92 1.68
full_fit_alloc_test 710950 12029752 16.92 13184651 18.55 1.10
long_busy_list_alloc_test 9431875 43990172 4.66 82970178 8.80 1.89
random_size_alloc_test 5033626 23061762 4.58 47158834 9.37 2.04
fix_align_alloc_test 1252514 15276910 12.20 31266116 24.96 2.05
random_size_align_alloc_te 1648501 14578321 8.84 25560052 15.51 1.75
align_shift_alloc_test 147 830 5.65 5692 38.72 6.86
pcpu_alloc_test 80732 125520 1.55 140864 1.74 1.12
Total Cycles 119240774314 763211341128 6.40 1390338696894 11.66 1.82
Sequential, 2 cpus
No KASAN KASAN original x baseline KASAN vmalloc x baseline x KASAN
fix_size_alloc_test
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Matthew Wilcox (Oracle)
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d8c6546b1a |
mm: introduce compound_nr()
Replace 1 << compound_order(page) with compound_nr(page). Minor improvements in readability. Link: http://lkml.kernel.org/r/20190721104612.19120-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Matthew Wilcox (Oracle)
|
a50b854e07 |
mm: introduce page_size()
Patch series "Make working with compound pages easier", v2. These three patches add three helpers and convert the appropriate places to use them. This patch (of 3): It's unnecessarily hard to find out the size of a potentially huge page. Replace 'PAGE_SIZE << compound_order(page)' with page_size(page). Link: http://lkml.kernel.org/r/20190721104612.19120-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Walter Wu
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ae8f06b31a |
kasan: add memory corruption identification for software tag-based mode
Add memory corruption identification at bug report for software tag-based mode. The report shows whether it is "use-after-free" or "out-of-bound" error instead of "invalid-access" error. This will make it easier for programmers to see the memory corruption problem. We extend the slab to store five old free pointer tag and free backtrace, we can check if the tagged address is in the slab record and make a good guess if the object is more like "use-after-free" or "out-of-bound". therefore every slab memory corruption can be identified whether it's "use-after-free" or "out-of-bound". [aryabinin@virtuozzo.com: simplify & clenup code] Link: https://lkml.kernel.org/r/3318f9d7-a760-3cc8-b700-f06108ae745f@virtuozzo.com] Link: http://lkml.kernel.org/r/20190821180332.11450-1-aryabinin@virtuozzo.com Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Andrey Konovalov <andreyknvl@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrey Ryabinin
|
00fb24a42a |
mm/kasan: fix false positive invalid-free reports with CONFIG_KASAN_SW_TAGS=y
The code like this:
ptr = kmalloc(size, GFP_KERNEL);
page = virt_to_page(ptr);
offset = offset_in_page(ptr);
kfree(page_address(page) + offset);
may produce false-positive invalid-free reports on the kernel with
CONFIG_KASAN_SW_TAGS=y.
In the example above we lose the original tag assigned to 'ptr', so
kfree() gets the pointer with 0xFF tag. In kfree() we check that 0xFF
tag is different from the tag in shadow hence print false report.
Instead of just comparing tags, do the following:
1) Check that shadow doesn't contain KASAN_TAG_INVALID. Otherwise it's
double-free and it doesn't matter what tag the pointer have.
2) If pointer tag is different from 0xFF, make sure that tag in the
shadow is the same as in the pointer.
Link: http://lkml.kernel.org/r/20190819172540.19581-1-aryabinin@virtuozzo.com
Fixes:
|
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Marco Elver
|
b5f6e0fc7d |
mm/kasan: change kasan_check_{read,write} to return boolean
This changes {,__}kasan_check_{read,write} functions to return a boolean
denoting if the access was valid or not.
[sfr@canb.auug.org.au: include types.h for "bool"]
Link: http://lkml.kernel.org/r/20190705184949.13cdd021@canb.auug.org.au
Link: http://lkml.kernel.org/r/20190626142014.141844-3-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Marco Elver
|
7d8ad890da |
mm/kasan: introduce __kasan_check_{read,write}
Patch series "mm/kasan: Add object validation in ksize()", v3.
This patch (of 5):
This introduces __kasan_check_{read,write}. __kasan_check functions may
be used from anywhere, even compilation units that disable instrumentation
selectively.
This change eliminates the need for the __KASAN_INTERNAL definition.
[elver@google.com: v5]
Link: http://lkml.kernel.org/r/20190708170706.174189-2-elver@google.com
Link: http://lkml.kernel.org/r/20190626142014.141844-2-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
Marco Elver
|
e896921900 |
mm/kasan: print frame description for stack bugs
This adds support for printing stack frame description on invalid stack accesses. The frame description is embedded by the compiler, which is parsed and then pretty-printed. Currently, we can only print the stack frame info for accesses to the task's own stack, but not accesses to other tasks' stacks. Example of what it looks like: page dumped because: kasan: bad access detected addr ffff8880673ef98a is located in stack of task insmod/2008 at offset 106 in frame: kasan_stack_oob+0x0/0xf5 [test_kasan] this frame has 2 objects: [32, 36) 'i' [96, 106) 'stack_array' Memory state around the buggy address: Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=198435 Link: http://lkml.kernel.org/r/20190522100048.146841-1-elver@google.com Signed-off-by: Marco Elver <elver@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
Nathan Chancellor
|
0600597c85 |
kasan: initialize tag to 0xff in __kasan_kmalloc
When building with -Wuninitialized and CONFIG_KASAN_SW_TAGS unset, Clang
warns:
mm/kasan/common.c:484:40: warning: variable 'tag' is uninitialized when
used here [-Wuninitialized]
kasan_unpoison_shadow(set_tag(object, tag), size);
^~~
set_tag ignores tag in this configuration but clang doesn't realize it at
this point in its pipeline, as it points to arch_kasan_set_tag as being
the point where it is used, which will later be expanded to (void
*)(object) without a use of tag. Initialize tag to 0xff, as it removes
this warning and doesn't change the meaning of the code.
Link: https://github.com/ClangBuiltLinux/linux/issues/465
Link: http://lkml.kernel.org/r/20190502163057.6603-1-natechancellor@gmail.com
Fixes:
|
||
|
Linus Torvalds
|
c620f7bd0b |
arm64 updates for 5.2
Mostly just incremental improvements here: - Introduce AT_HWCAP2 for advertising CPU features to userspace - Expose SVE2 availability to userspace - Support for "data cache clean to point of deep persistence" (DC PODP) - Honour "mitigations=off" on the cmdline and advertise status via sysfs - CPU timer erratum workaround (Neoverse-N1 #1188873) - Introduce perf PMU driver for the SMMUv3 performance counters - Add config option to disable the kuser helpers page for AArch32 tasks - Futex modifications to ensure liveness under contention - Rework debug exception handling to seperate kernel and user handlers - Non-critical fixes and cleanup -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEPxTL6PPUbjXGY88ct6xw3ITBYzQFAlzMFGgACgkQt6xw3ITB YzTicAf/TX1h1+ecbx4WJAa4qeiOCPoNpG9efldQumqJhKL44MR5bkhuShna5mwE ptm5qUXkZCxLTjzssZKnbdbgwa3t+emW8Of3D91IfI9akiZbMoDx5FGgcNbqjazb RLrhOFHwgontA38yppZN+DrL+sXbvif/CVELdHahkEx6KepSGaS2lmPXRmz/W56v 4yIRy/zxc3Dhjgfm3wKh72nBwoZdLiIc4mchd5pthNlR9E2idrYkQegG1C+gA00r o8uZRVOWgoh7H+QJE+xLUc8PaNCg8xqRRXOuZYg9GOz6hh7zSWhm+f1nRz9S2tIR gIgsCHNqoO2I3E1uJpAQXDGtt2kFhA== =ulpJ -----END PGP SIGNATURE----- Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux Pull arm64 updates from Will Deacon: "Mostly just incremental improvements here: - Introduce AT_HWCAP2 for advertising CPU features to userspace - Expose SVE2 availability to userspace - Support for "data cache clean to point of deep persistence" (DC PODP) - Honour "mitigations=off" on the cmdline and advertise status via sysfs - CPU timer erratum workaround (Neoverse-N1 #1188873) - Introduce perf PMU driver for the SMMUv3 performance counters - Add config option to disable the kuser helpers page for AArch32 tasks - Futex modifications to ensure liveness under contention - Rework debug exception handling to seperate kernel and user handlers - Non-critical fixes and cleanup" * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (92 commits) Documentation: Add ARM64 to kernel-parameters.rst arm64/speculation: Support 'mitigations=' cmdline option arm64: ssbs: Don't treat CPUs with SSBS as unaffected by SSB arm64: enable generic CPU vulnerabilites support arm64: add sysfs vulnerability show for speculative store bypass arm64: Fix size of __early_cpu_boot_status clocksource/arm_arch_timer: Use arch_timer_read_counter to access stable counters clocksource/arm_arch_timer: Remove use of workaround static key clocksource/arm_arch_timer: Drop use of static key in arch_timer_reg_read_stable clocksource/arm_arch_timer: Direcly assign set_next_event workaround arm64: Use arch_timer_read_counter instead of arch_counter_get_cntvct watchdog/sbsa: Use arch_timer_read_counter instead of arch_counter_get_cntvct ARM: vdso: Remove dependency with the arch_timer driver internals arm64: Apply ARM64_ERRATUM_1188873 to Neoverse-N1 arm64: Add part number for Neoverse N1 arm64: Make ARM64_ERRATUM_1188873 depend on COMPAT arm64: Restrict ARM64_ERRATUM_1188873 mitigation to AArch32 arm64: mm: Remove pte_unmap_nested() arm64: Fix compiler warning from pte_unmap() with -Wunused-but-set-variable arm64: compat: Reduce address limit for 64K pages ... |
||
|
Linus Torvalds
|
2c6a392cdd |
Merge branch 'core-stacktrace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull stack trace updates from Ingo Molnar:
"So Thomas looked at the stacktrace code recently and noticed a few
weirdnesses, and we all know how such stories of crummy kernel code
meeting German engineering perfection end: a 45-patch series to clean
it all up! :-)
Here's the changes in Thomas's words:
'Struct stack_trace is a sinkhole for input and output parameters
which is largely pointless for most usage sites. In fact if embedded
into other data structures it creates indirections and extra storage
overhead for no benefit.
Looking at all usage sites makes it clear that they just require an
interface which is based on a storage array. That array is either on
stack, global or embedded into some other data structure.
Some of the stack depot usage sites are outright wrong, but
fortunately the wrongness just causes more stack being used for
nothing and does not have functional impact.
Another oddity is the inconsistent termination of the stack trace
with ULONG_MAX. It's pointless as the number of entries is what
determines the length of the stored trace. In fact quite some call
sites remove the ULONG_MAX marker afterwards with or without nasty
comments about it. Not all architectures do that and those which do,
do it inconsistenly either conditional on nr_entries == 0 or
unconditionally.
The following series cleans that up by:
1) Removing the ULONG_MAX termination in the architecture code
2) Removing the ULONG_MAX fixups at the call sites
3) Providing plain storage array based interfaces for stacktrace
and stackdepot.
4) Cleaning up the mess at the callsites including some related
cleanups.
5) Removing the struct stack_trace based interfaces
This is not changing the struct stack_trace interfaces at the
architecture level, but it removes the exposure to the generic
code'"
* 'core-stacktrace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (45 commits)
x86/stacktrace: Use common infrastructure
stacktrace: Provide common infrastructure
lib/stackdepot: Remove obsolete functions
stacktrace: Remove obsolete functions
livepatch: Simplify stack trace retrieval
tracing: Remove the last struct stack_trace usage
tracing: Simplify stack trace retrieval
tracing: Make ftrace_trace_userstack() static and conditional
tracing: Use percpu stack trace buffer more intelligently
tracing: Simplify stacktrace retrieval in histograms
lockdep: Simplify stack trace handling
lockdep: Remove save argument from check_prev_add()
lockdep: Remove unused trace argument from print_circular_bug()
drm: Simplify stacktrace handling
dm persistent data: Simplify stack trace handling
dm bufio: Simplify stack trace retrieval
btrfs: ref-verify: Simplify stack trace retrieval
dma/debug: Simplify stracktrace retrieval
fault-inject: Simplify stacktrace retrieval
mm/page_owner: Simplify stack trace handling
...
|
||
Thomas Gleixner
|
880e049c9c |
mm/kasan: Simplify stacktrace handling
Replace the indirection through struct stack_trace by using the storage array based interfaces. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Alexander Potapenko <glider@google.com> Cc: kasan-dev@googlegroups.com Cc: linux-mm@kvack.org Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Akinobu Mita <akinobu.mita@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: iommu@lists.linux-foundation.org Cc: Robin Murphy <robin.murphy@arm.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: David Sterba <dsterba@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: linux-btrfs@vger.kernel.org Cc: dm-devel@redhat.com Cc: Mike Snitzer <snitzer@redhat.com> Cc: Alasdair Kergon <agk@redhat.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: intel-gfx@lists.freedesktop.org Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: dri-devel@lists.freedesktop.org Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Cc: Miroslav Benes <mbenes@suse.cz> Cc: linux-arch@vger.kernel.org Link: https://lkml.kernel.org/r/20190425094801.963261479@linutronix.de |
||
|
Thomas Gleixner
|
ead97a49ec |
mm/kasan: Remove the ULONG_MAX stack trace hackery
No architecture terminates the stack trace with ULONG_MAX anymore. Remove the cruft. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: kasan-dev@googlegroups.com Cc: linux-mm@kvack.org Link: https://lkml.kernel.org/r/20190410103644.750219625@linutronix.de |
||
Torsten Duwe
|
e2092740b7 |
kasan: Makefile: Replace -pg with CC_FLAGS_FTRACE
In preparation for arm64 supporting ftrace built on other compiler options, let's have Makefiles remove the $(CC_FLAGS_FTRACE) flags, whatever these may be, rather than assuming '-pg'. There should be no functional change as a result of this patch. Reviewed-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Torsten Duwe <duwe@suse.de> Signed-off-by: Will Deacon <will.deacon@arm.com> |
||
Peter Zijlstra
|
57b78a62e7 |
x86/uaccess, kasan: Fix KASAN vs SMAP
KASAN inserts extra code for every LOAD/STORE emitted by te compiler.
Much of this code is simple and safe to run with AC=1, however the
kasan_report() function, called on error, is most certainly not safe
to call with AC=1.
Therefore wrap kasan_report() in user_access_{save,restore}; which for
x86 SMAP, saves/restores EFLAGS and clears AC before calling the real
function.
Also ensure all the functions are without __fentry__ hook. The
function tracer is also not safe.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
||
Qian Cai
|
c412a769d2 |
kasan: fix variable 'tag' set but not used warning
set_tag() compiles away when CONFIG_KASAN_SW_TAGS=n, so make
arch_kasan_set_tag() a static inline function to fix warnings below.
mm/kasan/common.c: In function '__kasan_kmalloc':
mm/kasan/common.c:475:5: warning: variable 'tag' set but not used [-Wunused-but-set-variable]
u8 tag;
^~~
Link: http://lkml.kernel.org/r/20190307185244.54648-1-cai@lca.pw
Signed-off-by: Qian Cai <cai@lca.pw>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
Mike Rapoport
|
8a7f97b902 |
treewide: add checks for the return value of memblock_alloc*()
Add check for the return value of memblock_alloc*() functions and call
panic() in case of error. The panic message repeats the one used by
panicing memblock allocators with adjustment of parameters to include
only relevant ones.
The replacement was mostly automated with semantic patches like the one
below with manual massaging of format strings.
@@
expression ptr, size, align;
@@
ptr = memblock_alloc(size, align);
+ if (!ptr)
+ panic("%s: Failed to allocate %lu bytes align=0x%lx\n", __func__, size, align);
[anders.roxell@linaro.org: use '%pa' with 'phys_addr_t' type]
Link: http://lkml.kernel.org/r/20190131161046.21886-1-anders.roxell@linaro.org
[rppt@linux.ibm.com: fix format strings for panics after memblock_alloc]
Link: http://lkml.kernel.org/r/1548950940-15145-1-git-send-email-rppt@linux.ibm.com
[rppt@linux.ibm.com: don't panic if the allocation in sparse_buffer_init fails]
Link: http://lkml.kernel.org/r/20190131074018.GD28876@rapoport-lnx
[akpm@linux-foundation.org: fix xtensa printk warning]
Link: http://lkml.kernel.org/r/1548057848-15136-20-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Reviewed-by: Guo Ren <ren_guo@c-sky.com> [c-sky]
Acked-by: Paul Burton <paul.burton@mips.com> [MIPS]
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> [s390]
Reviewed-by: Juergen Gross <jgross@suse.com> [Xen]
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k]
Acked-by: Max Filippov <jcmvbkbc@gmail.com> [xtensa]
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
Andrey Konovalov
|
5c0198b6fb |
kasan: fix coccinelle warnings in kasan_p*_table
kasan_p4d_table(), kasan_pmd_table() and kasan_pud_table() are declared
as returning bool, but return 0 instead of false, which produces a
coccinelle warning. Fix it.
Link: http://lkml.kernel.org/r/1fa6fadf644859e8a6a8ecce258444b49be8c7ee.1551716733.git.andreyknvl@google.com
Fixes:
|
||
Arnd Bergmann
|
bcf6f55a0d |
kasan: fix kasan_check_read/write definitions
Building little-endian allmodconfig kernels on arm64 started failing with the generated atomic.h implementation, since we now try to call kasan helpers from the EFI stub: aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set': include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write' I suspect that we get similar problems in other files that explicitly disable KASAN for some reason but call atomic_t based helper functions. We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro that the compiler sets instead of checking CONFIG_KASAN, but this in turn requires a small hack in mm/kasan/common.c so we do see the extern declaration there instead of the inline function. Link: http://lkml.kernel.org/r/20181211133453.2835077-1-arnd@arndb.de Fixes: b1864b828644 ("locking/atomics: build atomic headers as required") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reported-by: Anders Roxell <anders.roxell@linaro.org> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au>, Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Andrey Ryabinin
|
7771bdbbfd |
kasan: remove use after scope bugs detection.
Use after scope bugs detector seems to be almost entirely useless for the linux kernel. It exists over two years, but I've seen only one valid bug so far [1]. And the bug was fixed before it has been reported. There were some other use-after-scope reports, but they were false-positives due to different reasons like incompatibility with structleak plugin. This feature significantly increases stack usage, especially with GCC < 9 version, and causes a 32K stack overflow. It probably adds performance penalty too. Given all that, let's remove use-after-scope detector entirely. While preparing this patch I've noticed that we mistakenly enable use-after-scope detection for clang compiler regardless of CONFIG_KASAN_EXTRA setting. This is also fixed now. [1] http://lkml.kernel.org/r/<20171129052106.rhgbjhhis53hkgfn@wfg-t540p.sh.intel.com> Link: http://lkml.kernel.org/r/20190111185842.13978-1-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Will Deacon <will.deacon@arm.com> [arm64] Cc: Qian Cai <cai@lca.pw> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Andrey Konovalov
|
dc15a8a254 |
kasan: prevent tracing of tags.c
Similarly to commit
|
||
|
Andrey Konovalov
|
3f41b60938 |
kasan: fix random seed generation for tag-based mode
There are two issues with assigning random percpu seeds right now: 1. We use for_each_possible_cpu() to iterate over cpus, but cpumask is not set up yet at the moment of kasan_init(), and thus we only set the seed for cpu #0. 2. A call to get_random_u32() always returns the same number and produces a message in dmesg, since the random subsystem is not yet initialized. Fix 1 by calling kasan_init_tags() after cpumask is set up. Fix 2 by using get_cycles() instead of get_random_u32(). This gives us lower quality random numbers, but it's good enough, as KASAN is meant to be used as a debugging tool and not a mitigation. Link: http://lkml.kernel.org/r/1f815cc914b61f3516ed4cc9bfd9eeca9bd5d9de.1550677973.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Andrey Konovalov
|
e1db95befb |
kasan: fix assigning tags twice
When an object is kmalloc()'ed, two hooks are called: kasan_slab_alloc() and kasan_kmalloc(). Right now we assign a tag twice, once in each of the hooks. Fix it by assigning a tag only in the former hook. Link: http://lkml.kernel.org/r/ce8c6431da735aa7ec051fd6497153df690eb021.1549921721.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgeniy Stepanov <eugenis@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Qian Cai <cai@lca.pw> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
Anders Roxell
|
0d0c8de878 |
kasan: mark file common so ftrace doesn't trace it
When option CONFIG_KASAN is enabled toghether with ftrace, function ftrace_graph_caller() gets in to a recursion, via functions kasan_check_read() and kasan_check_write(). Breakpoint 2, ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:179 179 mcount_get_pc x0 // function's pc (gdb) bt #0 ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:179 #1 0xffffff90101406c8 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:151 #2 0xffffff90106fd084 in kasan_check_write (p=0xffffffc06c170878, size=4) at ../mm/kasan/common.c:105 #3 0xffffff90104a2464 in atomic_add_return (v=<optimized out>, i=<optimized out>) at ./include/generated/atomic-instrumented.h:71 #4 atomic_inc_return (v=<optimized out>) at ./include/generated/atomic-fallback.h:284 #5 trace_graph_entry (trace=0xffffffc03f5ff380) at ../kernel/trace/trace_functions_graph.c:441 #6 0xffffff9010481774 in trace_graph_entry_watchdog (trace=<optimized out>) at ../kernel/trace/trace_selftest.c:741 #7 0xffffff90104a185c in function_graph_enter (ret=<optimized out>, func=<optimized out>, frame_pointer=18446743799894897728, retp=<optimized out>) at ../kernel/trace/trace_functions_graph.c:196 #8 0xffffff9010140628 in prepare_ftrace_return (self_addr=18446743592948977792, parent=0xffffffc03f5ff418, frame_pointer=18446743799894897728) at ../arch/arm64/kernel/ftrace.c:231 #9 0xffffff90101406f4 in ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:182 Backtrace stopped: previous frame identical to this frame (corrupt stack?) (gdb) Rework so that the kasan implementation isn't traced. Link: http://lkml.kernel.org/r/20181212183447.15890-1-anders.roxell@linaro.org Signed-off-by: Anders Roxell <anders.roxell@linaro.org> Acked-by: Dmitry Vyukov <dvyukov@google.com> Tested-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
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Andrey Konovalov
|
a3fe7cdf02 |
kasan: fix krealloc handling for tag-based mode
Right now tag-based KASAN can retag the memory that is reallocated via krealloc and return a differently tagged pointer even if the same slab object gets used and no reallocated technically happens. There are a few issues with this approach. One is that krealloc callers can't rely on comparing the return value with the passed argument to check whether reallocation happened. Another is that if a caller knows that no reallocation happened, that it can access object memory through the old pointer, which leads to false positives. Look at nf_ct_ext_add() to see an example. Fix this by keeping the same tag if the memory don't actually gets reallocated during krealloc. Link: http://lkml.kernel.org/r/bb2a71d17ed072bcc528cbee46fcbd71a6da3be4.1546540962.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrey Konovalov
|
eb214f2dda |
kasan, arm64: use ARCH_SLAB_MINALIGN instead of manual aligning
Instead of changing cache->align to be aligned to KASAN_SHADOW_SCALE_SIZE in kasan_cache_create() we can reuse the ARCH_SLAB_MINALIGN macro. Link: http://lkml.kernel.org/r/52ddd881916bcc153a9924c154daacde78522227.1546540962.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Suggested-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Joel Fernandes (Google)
|
4cf5892495 |
mm: treewide: remove unused address argument from pte_alloc functions
Patch series "Add support for fast mremap".
This series speeds up the mremap(2) syscall by copying page tables at
the PMD level even for non-THP systems. There is concern that the extra
'address' argument that mremap passes to pte_alloc may do something
subtle architecture related in the future that may make the scheme not
work. Also we find that there is no point in passing the 'address' to
pte_alloc since its unused. This patch therefore removes this argument
tree-wide resulting in a nice negative diff as well. Also ensuring
along the way that the enabled architectures do not do anything funky
with the 'address' argument that goes unnoticed by the optimization.
Build and boot tested on x86-64. Build tested on arm64. The config
enablement patch for arm64 will be posted in the future after more
testing.
The changes were obtained by applying the following Coccinelle script.
(thanks Julia for answering all Coccinelle questions!).
Following fix ups were done manually:
* Removal of address argument from pte_fragment_alloc
* Removal of pte_alloc_one_fast definitions from m68k and microblaze.
// Options: --include-headers --no-includes
// Note: I split the 'identifier fn' line, so if you are manually
// running it, please unsplit it so it runs for you.
virtual patch
@pte_alloc_func_def depends on patch exists@
identifier E2;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
type T2;
@@
fn(...
- , T2 E2
)
{ ... }
@pte_alloc_func_proto_noarg depends on patch exists@
type T1, T2, T3, T4;
identifier fn =~ "^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
(
- T3 fn(T1, T2);
+ T3 fn(T1);
|
- T3 fn(T1, T2, T4);
+ T3 fn(T1, T2);
)
@pte_alloc_func_proto depends on patch exists@
identifier E1, E2, E4;
type T1, T2, T3, T4;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
(
- T3 fn(T1 E1, T2 E2);
+ T3 fn(T1 E1);
|
- T3 fn(T1 E1, T2 E2, T4 E4);
+ T3 fn(T1 E1, T2 E2);
)
@pte_alloc_func_call depends on patch exists@
expression E2;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
fn(...
-, E2
)
@pte_alloc_macro depends on patch exists@
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
identifier a, b, c;
expression e;
position p;
@@
(
- #define fn(a, b, c) e
+ #define fn(a, b) e
|
- #define fn(a, b) e
+ #define fn(a) e
)
Link: http://lkml.kernel.org/r/20181108181201.88826-2-joelaf@google.com
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Suggested-by: Kirill A. Shutemov <kirill@shutemov.name>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
||
Arun KS
|
ca79b0c211 |
mm: convert totalram_pages and totalhigh_pages variables to atomic
totalram_pages and totalhigh_pages are made static inline function. Main motivation was that managed_page_count_lock handling was complicating things. It was discussed in length here, https://lore.kernel.org/patchwork/patch/995739/#1181785 So it seemes better to remove the lock and convert variables to atomic, with preventing poteintial store-to-read tearing as a bonus. [akpm@linux-foundation.org: coding style fixes] Link: http://lkml.kernel.org/r/1542090790-21750-4-git-send-email-arunks@codeaurora.org Signed-off-by: Arun KS <arunks@codeaurora.org> Suggested-by: Michal Hocko <mhocko@suse.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
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Andrey Konovalov
|
e886bf9d9a |
kasan: add SPDX-License-Identifier mark to source files
This patch adds a "SPDX-License-Identifier: GPL-2.0" mark to all source files under mm/kasan. Link: http://lkml.kernel.org/r/bce2d1e618afa5142e81961ab8fa4b4165337380.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
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Andrey Konovalov
|
66afc7f1e0 |
kasan: add __must_check annotations to kasan hooks
This patch adds __must_check annotations to kasan hooks that return a pointer to make sure that a tagged pointer always gets propagated. Link: http://lkml.kernel.org/r/03b269c5e453945f724bfca3159d4e1333a8fb1c.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Suggested-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
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Andrey Konovalov
|
2813b9c029 |
kasan, mm, arm64: tag non slab memory allocated via pagealloc
Tag-based KASAN doesn't check memory accesses through pointers tagged with 0xff. When page_address is used to get pointer to memory that corresponds to some page, the tag of the resulting pointer gets set to 0xff, even though the allocated memory might have been tagged differently. For slab pages it's impossible to recover the correct tag to return from page_address, since the page might contain multiple slab objects tagged with different values, and we can't know in advance which one of them is going to get accessed. For non slab pages however, we can recover the tag in page_address, since the whole page was marked with the same tag. This patch adds tagging to non slab memory allocated with pagealloc. To set the tag of the pointer returned from page_address, the tag gets stored to page->flags when the memory gets allocated. Link: http://lkml.kernel.org/r/d758ddcef46a5abc9970182b9137e2fbee202a2c.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
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Andrey Konovalov
|
7f94ffbc4c |
kasan: add hooks implementation for tag-based mode
This commit adds tag-based KASAN specific hooks implementation and adjusts common generic and tag-based KASAN ones. 1. When a new slab cache is created, tag-based KASAN rounds up the size of the objects in this cache to KASAN_SHADOW_SCALE_SIZE (== 16). 2. On each kmalloc tag-based KASAN generates a random tag, sets the shadow memory, that corresponds to this object to this tag, and embeds this tag value into the top byte of the returned pointer. 3. On each kfree tag-based KASAN poisons the shadow memory with a random tag to allow detection of use-after-free bugs. The rest of the logic of the hook implementation is very much similar to the one provided by generic KASAN. Tag-based KASAN saves allocation and free stack metadata to the slab object the same way generic KASAN does. Link: http://lkml.kernel.org/r/bda78069e3b8422039794050ddcb2d53d053ed41.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
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Andrey Konovalov
|
121e8f81d3 |
kasan: add bug reporting routines for tag-based mode
This commit adds rountines, that print tag-based KASAN error reports. Those are quite similar to generic KASAN, the difference is: 1. The way tag-based KASAN finds the first bad shadow cell (with a mismatching tag). Tag-based KASAN compares memory tags from the shadow memory to the pointer tag. 2. Tag-based KASAN reports all bugs with the "KASAN: invalid-access" header. Also simplify generic KASAN find_first_bad_addr. Link: http://lkml.kernel.org/r/aee6897b1bd077732a315fd84c6b4f234dbfdfcb.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Andrey Konovalov
|
11cd3cd69a |
kasan: split out generic_report.c from report.c
Move generic KASAN specific error reporting routines to generic_report.c without any functional changes, leaving common error reporting code in report.c to be later reused by tag-based KASAN. Link: http://lkml.kernel.org/r/ba48c32f8e5aefedee78998ccff0413bee9e0f5b.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Andrey Konovalov
|
3c9e3aa110 |
kasan: add tag related helper functions
This commit adds a few helper functions, that are meant to be used to work with tags embedded in the top byte of kernel pointers: to set, to get or to reset the top byte. Link: http://lkml.kernel.org/r/f6c6437bb8e143bc44f42c3c259c62e734be7935.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
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Andrey Konovalov
|
080eb83f54 |
kasan: initialize shadow to 0xff for tag-based mode
A tag-based KASAN shadow memory cell contains a memory tag, that corresponds to the tag in the top byte of the pointer, that points to that memory. The native top byte value of kernel pointers is 0xff, so with tag-based KASAN we need to initialize shadow memory to 0xff. [cai@lca.pw: arm64: skip kmemleak for KASAN again\ Link: http://lkml.kernel.org/r/20181226020550.63712-1-cai@lca.pw Link: http://lkml.kernel.org/r/5cc1b789aad7c99cf4f3ec5b328b147ad53edb40.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
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Andrey Konovalov
|
9577dd7486 |
kasan: rename kasan_zero_page to kasan_early_shadow_page
With tag based KASAN mode the early shadow value is 0xff and not 0x00, so this patch renames kasan_zero_(page|pte|pmd|pud|p4d) to kasan_early_shadow_(page|pte|pmd|pud|p4d) to avoid confusion. Link: http://lkml.kernel.org/r/3fed313280ebf4f88645f5b89ccbc066d320e177.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Suggested-by: Mark Rutland <mark.rutland@arm.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Andrey Konovalov
|
2bd926b439 |
kasan: add CONFIG_KASAN_GENERIC and CONFIG_KASAN_SW_TAGS
This commit splits the current CONFIG_KASAN config option into two: 1. CONFIG_KASAN_GENERIC, that enables the generic KASAN mode (the one that exists now); 2. CONFIG_KASAN_SW_TAGS, that enables the software tag-based KASAN mode. The name CONFIG_KASAN_SW_TAGS is chosen as in the future we will have another hardware tag-based KASAN mode, that will rely on hardware memory tagging support in arm64. With CONFIG_KASAN_SW_TAGS enabled, compiler options are changed to instrument kernel files with -fsantize=kernel-hwaddress (except the ones for which KASAN_SANITIZE := n is set). Both CONFIG_KASAN_GENERIC and CONFIG_KASAN_SW_TAGS support both CONFIG_KASAN_INLINE and CONFIG_KASAN_OUTLINE instrumentation modes. This commit also adds empty placeholder (for now) implementation of tag-based KASAN specific hooks inserted by the compiler and adjusts common hooks implementation. While this commit adds the CONFIG_KASAN_SW_TAGS config option, this option is not selectable, as it depends on HAVE_ARCH_KASAN_SW_TAGS, which we will enable once all the infrastracture code has been added. Link: http://lkml.kernel.org/r/b2550106eb8a68b10fefbabce820910b115aa853.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrey Konovalov
|
b938fcf427 |
kasan: rename source files to reflect the new naming scheme
We now have two KASAN modes: generic KASAN and tag-based KASAN. Rename kasan.c to generic.c to reflect that. Also rename kasan_init.c to init.c as it contains initialization code for both KASAN modes. Link: http://lkml.kernel.org/r/88c6fd2a883e459e6242030497230e5fb0d44d44.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrey Konovalov
|
bffa986c6f |
kasan: move common generic and tag-based code to common.c
Tag-based KASAN reuses a significant part of the generic KASAN code, so move the common parts to common.c without any functional changes. Link: http://lkml.kernel.org/r/114064d002356e03bb8cc91f7835e20dc61b51d9.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
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Andrey Konovalov
|
0116523cff |
kasan, mm: change hooks signatures
Patch series "kasan: add software tag-based mode for arm64", v13. This patchset adds a new software tag-based mode to KASAN [1]. (Initially this mode was called KHWASAN, but it got renamed, see the naming rationale at the end of this section). The plan is to implement HWASan [2] for the kernel with the incentive, that it's going to have comparable to KASAN performance, but in the same time consume much less memory, trading that off for somewhat imprecise bug detection and being supported only for arm64. The underlying ideas of the approach used by software tag-based KASAN are: 1. By using the Top Byte Ignore (TBI) arm64 CPU feature, we can store pointer tags in the top byte of each kernel pointer. 2. Using shadow memory, we can store memory tags for each chunk of kernel memory. 3. On each memory allocation, we can generate a random tag, embed it into the returned pointer and set the memory tags that correspond to this chunk of memory to the same value. 4. By using compiler instrumentation, before each memory access we can add a check that the pointer tag matches the tag of the memory that is being accessed. 5. On a tag mismatch we report an error. With this patchset the existing KASAN mode gets renamed to generic KASAN, with the word "generic" meaning that the implementation can be supported by any architecture as it is purely software. The new mode this patchset adds is called software tag-based KASAN. The word "tag-based" refers to the fact that this mode uses tags embedded into the top byte of kernel pointers and the TBI arm64 CPU feature that allows to dereference such pointers. The word "software" here means that shadow memory manipulation and tag checking on pointer dereference is done in software. As it is the only tag-based implementation right now, "software tag-based" KASAN is sometimes referred to as simply "tag-based" in this patchset. A potential expansion of this mode is a hardware tag-based mode, which would use hardware memory tagging support (announced by Arm [3]) instead of compiler instrumentation and manual shadow memory manipulation. Same as generic KASAN, software tag-based KASAN is strictly a debugging feature. [1] https://www.kernel.org/doc/html/latest/dev-tools/kasan.html [2] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html [3] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architecture-2018-developments-armv85a ====== Rationale On mobile devices generic KASAN's memory usage is significant problem. One of the main reasons to have tag-based KASAN is to be able to perform a similar set of checks as the generic one does, but with lower memory requirements. Comment from Vishwath Mohan <vishwath@google.com>: I don't have data on-hand, but anecdotally both ASAN and KASAN have proven problematic to enable for environments that don't tolerate the increased memory pressure well. This includes (a) Low-memory form factors - Wear, TV, Things, lower-tier phones like Go, (c) Connected components like Pixel's visual core [1]. These are both places I'd love to have a low(er) memory footprint option at my disposal. Comment from Evgenii Stepanov <eugenis@google.com>: Looking at a live Android device under load, slab (according to /proc/meminfo) + kernel stack take 8-10% available RAM (~350MB). KASAN's overhead of 2x - 3x on top of it is not insignificant. Not having this overhead enables near-production use - ex. running KASAN/KHWASAN kernel on a personal, daily-use device to catch bugs that do not reproduce in test configuration. These are the ones that often cost the most engineering time to track down. CPU overhead is bad, but generally tolerable. RAM is critical, in our experience. Once it gets low enough, OOM-killer makes your life miserable. [1] https://www.blog.google/products/pixel/pixel-visual-core-image-processing-and-machine-learning-pixel-2/ ====== Technical details Software tag-based KASAN mode is implemented in a very similar way to the generic one. This patchset essentially does the following: 1. TCR_TBI1 is set to enable Top Byte Ignore. 2. Shadow memory is used (with a different scale, 1:16, so each shadow byte corresponds to 16 bytes of kernel memory) to store memory tags. 3. All slab objects are aligned to shadow scale, which is 16 bytes. 4. All pointers returned from the slab allocator are tagged with a random tag and the corresponding shadow memory is poisoned with the same value. 5. Compiler instrumentation is used to insert tag checks. Either by calling callbacks or by inlining them (CONFIG_KASAN_OUTLINE and CONFIG_KASAN_INLINE flags are reused). 6. When a tag mismatch is detected in callback instrumentation mode KASAN simply prints a bug report. In case of inline instrumentation, clang inserts a brk instruction, and KASAN has it's own brk handler, which reports the bug. 7. The memory in between slab objects is marked with a reserved tag, and acts as a redzone. 8. When a slab object is freed it's marked with a reserved tag. Bug detection is imprecise for two reasons: 1. We won't catch some small out-of-bounds accesses, that fall into the same shadow cell, as the last byte of a slab object. 2. We only have 1 byte to store tags, which means we have a 1/256 probability of a tag match for an incorrect access (actually even slightly less due to reserved tag values). Despite that there's a particular type of bugs that tag-based KASAN can detect compared to generic KASAN: use-after-free after the object has been allocated by someone else. ====== Testing Some kernel developers voiced a concern that changing the top byte of kernel pointers may lead to subtle bugs that are difficult to discover. To address this concern deliberate testing has been performed. It doesn't seem feasible to do some kind of static checking to find potential issues with pointer tagging, so a dynamic approach was taken. All pointer comparisons/subtractions have been instrumented in an LLVM compiler pass and a kernel module that would print a bug report whenever two pointers with different tags are being compared/subtracted (ignoring comparisons with NULL pointers and with pointers obtained by casting an error code to a pointer type) has been used. Then the kernel has been booted in QEMU and on an Odroid C2 board and syzkaller has been run. This yielded the following results. The two places that look interesting are: is_vmalloc_addr in include/linux/mm.h is_kernel_rodata in mm/util.c Here we compare a pointer with some fixed untagged values to make sure that the pointer lies in a particular part of the kernel address space. Since tag-based KASAN doesn't add tags to pointers that belong to rodata or vmalloc regions, this should work as is. To make sure debug checks to those two functions that check that the result doesn't change whether we operate on pointers with or without untagging has been added. A few other cases that don't look that interesting: Comparing pointers to achieve unique sorting order of pointee objects (e.g. sorting locks addresses before performing a double lock): tty_ldisc_lock_pair_timeout in drivers/tty/tty_ldisc.c pipe_double_lock in fs/pipe.c unix_state_double_lock in net/unix/af_unix.c lock_two_nondirectories in fs/inode.c mutex_lock_double in kernel/events/core.c ep_cmp_ffd in fs/eventpoll.c fsnotify_compare_groups fs/notify/mark.c Nothing needs to be done here, since the tags embedded into pointers don't change, so the sorting order would still be unique. Checks that a pointer belongs to some particular allocation: is_sibling_entry in lib/radix-tree.c object_is_on_stack in include/linux/sched/task_stack.h Nothing needs to be done here either, since two pointers can only belong to the same allocation if they have the same tag. Overall, since the kernel boots and works, there are no critical bugs. As for the rest, the traditional kernel testing way (use until fails) is the only one that looks feasible. Another point here is that tag-based KASAN is available under a separate config option that needs to be deliberately enabled. Even though it might be used in a "near-production" environment to find bugs that are not found during fuzzing or running tests, it is still a debug tool. ====== Benchmarks The following numbers were collected on Odroid C2 board. Both generic and tag-based KASAN were used in inline instrumentation mode. Boot time [1]: * ~1.7 sec for clean kernel * ~5.0 sec for generic KASAN * ~5.0 sec for tag-based KASAN Network performance [2]: * 8.33 Gbits/sec for clean kernel * 3.17 Gbits/sec for generic KASAN * 2.85 Gbits/sec for tag-based KASAN Slab memory usage after boot [3]: * ~40 kb for clean kernel * ~105 kb (~260% overhead) for generic KASAN * ~47 kb (~20% overhead) for tag-based KASAN KASAN memory overhead consists of three main parts: 1. Increased slab memory usage due to redzones. 2. Shadow memory (the whole reserved once during boot). 3. Quaratine (grows gradually until some preset limit; the more the limit, the more the chance to detect a use-after-free). Comparing tag-based vs generic KASAN for each of these points: 1. 20% vs 260% overhead. 2. 1/16th vs 1/8th of physical memory. 3. Tag-based KASAN doesn't require quarantine. [1] Time before the ext4 driver is initialized. [2] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`. [3] Measured as `cat /proc/meminfo | grep Slab`. ====== Some notes A few notes: 1. The patchset can be found here: https://github.com/xairy/kasan-prototype/tree/khwasan 2. Building requires a recent Clang version (7.0.0 or later). 3. Stack instrumentation is not supported yet and will be added later. This patch (of 25): Tag-based KASAN changes the value of the top byte of pointers returned from the kernel allocation functions (such as kmalloc). This patch updates KASAN hooks signatures and their usage in SLAB and SLUB code to reflect that. Link: http://lkml.kernel.org/r/aec2b5e3973781ff8a6bb6760f8543643202c451.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |