Linus Torvalds a50026bdb8 iov_iter: get rid of 'copy_mc' flag ... This flag is only set by one single user: the magical core dumping code that looks up user pages one by one, and then writes them out using their kernel addresses (by using a BVEC_ITER). That actually ends up being a huge problem, because while we do use copy_mc_to_kernel() for this case and it is able to handle the possible machine checks involved, nothing else is really ready to handle the failures caused by the machine check. In particular, as reported by Tong Tiangen, we don't actually support fault_in_iov_iter_readable() on a machine check area. As a result, the usual logic for writing things to a file under a filesystem lock, which involves doing a copy with page faults disabled and then if that fails trying to fault pages in without holding the locks with fault_in_iov_iter_readable() does not work at all. We could decide to always just make the MC copy "succeed" (and filling the destination with zeroes), and that would then create a core dump file that just ignores any machine checks. But honestly, this single special case has been problematic before, and means that all the normal iov_iter code ends up slightly more complex and slower. See for example commit c9eec08bac ("iov_iter: Don't deal with iter->copy_mc in memcpy_from_iter_mc()") where David Howells re-organized the code just to avoid having to check the 'copy_mc' flags inside the inner iov_iter loops. So considering that we have exactly one user, and that one user is a non-critical special case that doesn't actually ever trigger in real life (Tong found this with manual error injection), the sane solution is to just decide that the onus on handling the machine check lines on that user instead. Ergo, do the copy_mc_to_kernel() in the core dump logic itself, copying the user data to a stable kernel page before writing it out. Fixes: f1982740f5 ("iov_iter: Convert iterate*() to inline funcs") Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Tong Tiangen <tongtiangen@huawei.com> Link: https://lore.kernel.org/r/20240305133336.3804360-1-tongtiangen@huawei.com Link: https://lore.kernel.org/all/4e80924d-9c85-f13a-722a-6a5d2b1c225a@huawei.com/ Tested-by: David Howells <dhowells@redhat.com> Reviewed-by: David Howells <dhowells@redhat.com> Reviewed-by: Jens Axboe <axboe@kernel.dk> Reported-by: Tong Tiangen <tongtiangen@huawei.com> Signed-off-by: Christian Brauner <brauner@kernel.org>		2024-03-06 10:52:12 +01:00
..
842
crypto	crypto: lib/mpi - Fix unexpected pointer access in mpi_ec_init	2023-12-22 12:30:19 +08:00
dim	linux/dim: Do nothing if no time delta between samples	2023-05-09 11:06:45 +02:00
fonts	powerpc: Use shared font data	2023-10-01 23:09:02 +11:00
kunit	kunit: device: Unregister the kunit_bus on shutdown	2024-02-06 17:07:37 -07:00
livepatch
lz4
lzo
math	lib/math/int_log: Replace LGPL-2.1-or-later boilerplate with SPDX identifier	2023-07-09 22:47:50 +01:00
pldmfw	lib: remove MODULE_LICENSE in non-modules	2023-04-13 13:13:53 -07:00
raid6	s390/fpu: get rid of MACHINE_HAS_VX	2023-12-11 14:33:07 +01:00
reed_solomon
test_fortify	string: Remove strlcpy()	2024-01-19 11:59:11 -08:00
vdso	vdso: Improve cmd_vdso_check to check all dynamic relocations	2023-03-21 21:15:34 +01:00
xz	arch: Remove Itanium (IA-64) architecture	2023-09-11 08:13:17 +00:00
zlib_deflate	lib/zlib: DFLTCC deflate does not write all available bits for Z_NO_FLUSH	2023-02-27 17:00:14 -08:00
zlib_dfltcc	lib/zlib: remove redundation assignement of avail_in dfltcc_gdht()	2023-02-02 22:50:10 -08:00
zlib_inflate	lib/zlib: Split deflate and inflate states for DFLTCC	2023-02-02 22:50:09 -08:00
zstd	zstd: Fix array-index-out-of-bounds UBSAN warning	2023-11-14 17:12:52 -08:00
.gitignore
argv_split.c	argv_split: fix kernel-doc warnings	2023-09-19 13:21:33 -07:00
ashldi3.c
ashrdi3.c
asn1_decoder.c
asn1_encoder.c
assoc_array.c
atomic64_test.c
atomic64.c
audit.c
base64.c
bcd.c
bch.c	lib/bch.c: use bitrev instead of internal logic	2023-08-18 10:18:58 -07:00
bitfield_kunit.c
bitmap-str.c	lib/bitmap: split-out string-related operations to a separate files	2023-10-14 20:25:22 -07:00
bitmap.c	bitmap: move bitmap_*_region() functions to bitmap.h	2023-10-16 16:14:45 -07:00
bitrev.c
bootconfig-data.S
bootconfig.c
bsearch.c
btree.c	btree: remove MODULE_LICENSE in non-modules	2023-04-13 13:13:54 -07:00
bucket_locks.c
bug.c	cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG	2023-01-31 15:01:45 +01:00
build_OID_registry
buildid.c	ELF: fix all "Elf" typos	2023-04-08 13:45:37 -07:00
bust_spinlocks.c
check_signature.c
checksum_kunit.c	kunit: Fix again checksum tests on big endian CPUs	2024-02-29 09:16:02 -08:00
checksum.c
closure.c	closures: CLOSURE_CALLBACK() to fix type punning	2023-11-24 00:29:58 -05:00
clz_ctz.c	lib/clz_ctz.c: Fix __clzdi2() and __ctzdi2() for 32-bit kernels	2023-08-25 13:22:10 -07:00
clz_tab.c
cmdline_kunit.c
cmdline.c
cmpdi2.c
compat_audit.c
cpu_rmap.c	lib: cpu_rmap: Fix potential use-after-free in irq_cpu_rmap_release()	2023-06-07 21:25:00 -07:00
cpumask_kunit.c	cpumask: re-introduce constant-sized cpumask optimizations	2023-03-05 14:30:34 -08:00
cpumask.c	bitmap patches for v6.7	2023-11-03 07:08:36 -10:00
crc4.c
crc7.c
crc8.c
crc16.c
crc32.c
crc32defs.h
crc32test.c
crc64-rocksoft.c
crc64.c
crc-ccitt.c	lib: crc_ccitt_false() is identical to crc_itu_t()	2023-12-29 12:22:26 -08:00
crc-itu-t.c
crc-t10dif.c
ctype.c
debug_info.c
debug_locks.c
debugobjects.c	debugobjects: Stop accessing objects after releasing hash bucket lock	2023-11-22 10:41:46 +01:00
dec_and_lock.c	perf: Fix perf_event_pmu_context serialization	2023-01-31 20:37:18 +01:00
decompress_bunzip2.c
decompress_inflate.c	decompressor: provide missing prototypes	2023-06-09 17:44:17 -07:00
decompress_unlz4.c
decompress_unlzma.c
decompress_unlzo.c
decompress_unxz.c	arch: Remove Itanium (IA-64) architecture	2023-09-11 08:13:17 +00:00
decompress_unzstd.c	decompressor: provide missing prototypes	2023-06-09 17:44:17 -07:00
decompress.c
devmem_is_allowed.c	lib: devmem_is_allowed: include linux/io.h	2023-06-09 17:44:15 -07:00
devres.c	devres: show which resource was invalid in __devm_ioremap_resource()	2023-06-23 17:04:04 -07:00
dhry_1.c	lib: dhry: fix sleeping allocations inside non-preemptable section	2023-07-08 09:29:32 -07:00
dhry_2.c	lib: add Dhrystone benchmark test	2023-02-02 22:50:01 -08:00
dhry_run.c	lib: dhry: fix unstable smp_processor_id(_) usage	2023-03-23 17:18:35 -07:00
dhry.h	lib: add Dhrystone benchmark test	2023-02-02 22:50:01 -08:00
digsig.c
dump_stack.c
dynamic_debug.c	dyndbg: add source filename to prefix	2023-08-04 15:28:41 +02:00
dynamic_queue_limits.c
earlycpio.c
errname.c	parisc: Drop the HP-UX ENOSYM and EREMOTERELEASE error codes	2023-11-25 09:43:18 +01:00
error-inject.c	lib: error-inject: remove error checking for debugfs_create_dir()	2023-08-18 10:18:55 -07:00
errseq.c
extable.c
fault-inject-usercopy.c
fault-inject.c	fault-inject: allow configuration via configfs	2023-04-13 07:38:54 -06:00
fdt_addresses.c
fdt_empty_tree.c
fdt_ro.c
fdt_rw.c
fdt_strerror.c
fdt_sw.c
fdt_wip.c
fdt.c
find_bit_benchmark.c
find_bit.c	cpumask: introduce for_each_cpu_or	2023-03-19 10:02:04 -07:00
flex_proportions.c
fortify_kunit.c	fortify: test: Use kunit_device	2023-12-18 13:28:08 -07:00
fw_table.c	cxl for v6.8	2024-01-18 16:22:43 -08:00
gen_crc32table.c
gen_crc64table.c
genalloc.c	Devicetree include cleanups for v6.6:	2023-08-30 17:04:28 -07:00
generic-radix-tree.c	lib/generic-radix-tree.c: Add peek_prev()	2023-10-19 14:47:33 -04:00
glob.c
globtest.c
group_cpus.c	lib/group_cpus.c: avoid acquiring cpu hotplug lock in group_cpus_evenly	2023-12-06 16:12:46 -08:00
hashtable_test.c	lib/hashtable_test.c: add test for the hashtable structure	2023-02-08 14:28:17 -07:00
hexdump.c
hweight.c
idr.c	ida: Fix crash in ida_free when the bitmap is empty	2023-12-21 10:02:28 -08:00
inflate.c
interval_tree_test.c
interval_tree.c	interval-tree: Add a utility to iterate over spans in an interval tree	2022-11-29 16:34:15 -04:00
iomap_copy.c
iomap.c
iommu-helper.c
iov_iter.c	iov_iter: get rid of 'copy_mc' flag	2024-03-06 10:52:12 +01:00
irq_poll.c
irq_regs.c
is_signed_type_kunit.c	lib: assume char is unsigned	2022-11-19 00:56:15 +01:00
is_single_threaded.c
kasprintf.c
Kconfig	lib/stackdepot: use fixed-sized slots for stack records	2023-12-10 16:51:44 -08:00
Kconfig.debug	lib/Kconfig.debug: TEST_IOV_ITER depends on MMU	2024-02-20 14:20:48 -08:00
Kconfig.kasan	Many singleton patches against the MM code. The patch series which	2024-01-09 11:18:47 -08:00
Kconfig.kcsan	Kernel concurrency sanitizer (KCSAN) updates for v6.3	2023-02-25 13:02:20 -08:00
Kconfig.kfence	mm/slab: remove CONFIG_SLAB from all Kconfig and Makefile	2023-12-05 11:14:40 +01:00
Kconfig.kgdb
Kconfig.kmsan	mm/slab: remove CONFIG_SLAB from all Kconfig and Makefile	2023-12-05 11:14:40 +01:00
Kconfig.ubsan	ubsan: Clarify Kconfig text for CONFIG_UBSAN_TRAP	2023-07-17 16:05:19 -07:00
kfifo.c
klist.c
kobject_uevent.c	kobject: Replace strlcpy with strscpy	2023-09-22 09:50:56 -07:00
kobject.c	Revert "kobject: Remove redundant checks for whether ktype is NULL"	2024-02-08 16:39:25 +00:00
kstrtox.c	kstrtox: consistently use _tolower()	2023-08-21 13:46:25 -07:00
kstrtox.h
kunit_iov_iter.c	iov_iter: Kunit tests for page extraction	2023-09-09 15:11:49 -07:00
libcrc32c.c	libcrc32c: remove crc32c_impl	2023-04-17 18:01:23 +02:00
linear_ranges.c
list_debug.c	list: Introduce CONFIG_LIST_HARDENED	2023-08-15 14:57:25 -07:00
list_sort.c
list-test.c	list: test: Test the klist structure	2023-03-31 09:21:35 -06:00
llist.c	llist: add llist_del_first_this()	2023-10-16 12:44:06 -04:00
locking-selftest-hardirq.h
locking-selftest-mutex.h
locking-selftest-rlock-hardirq.h
locking-selftest-rlock-softirq.h
locking-selftest-rlock.h
locking-selftest-rsem.h
locking-selftest-rtmutex.h
locking-selftest-softirq.h
locking-selftest-spin-hardirq.h
locking-selftest-spin-softirq.h
locking-selftest-spin.h
locking-selftest-wlock-hardirq.h
locking-selftest-wlock-softirq.h
locking-selftest-wlock.h
locking-selftest-wsem.h
locking-selftest.c	lockdep/selftests: Use SBRM APIs for wait context tests	2023-07-26 12:29:13 +02:00
lockref.c	lockref: stop doing cpu_relax in the cmpxchg loop	2023-01-13 14:35:38 -06:00
logic_iomem.c
logic_pio.c	minmax: add in_range() macro	2023-08-24 16:20:18 -07:00
lru_cache.c	lru_cache: remove unused lc_private, lc_set, lc_index_of	2022-11-22 19:38:39 -07:00
lshrdi3.c
lwq.c	lib: add light-weight queuing mechanism.	2023-10-16 12:44:06 -04:00
Makefile	cxl for v6.7	2023-11-04 16:20:36 -10:00
maple_tree.c	maple_tree: avoid checking other gaps after getting the largest gap	2023-12-20 14:48:14 -08:00
memcat_p.c
memcpy_kunit.c	kunit: memcpy: Mark tests as slow using test attributes	2023-07-26 13:29:28 -06:00
memory-notifier-error-inject.c
memregion.c
memweight.c
muldi3.c
net_utils.c	mac_pton: Clean up the header inclusions	2023-06-06 13:18:32 +02:00
netdev-notifier-error-inject.c
nlattr.c	netlink: add nla be16/32 types to minlen array	2024-02-22 19:01:55 -08:00
nmi_backtrace.c	nmi_backtrace: allow excluding an arbitrary CPU	2023-08-18 10:19:00 -07:00
notifier-error-inject.c	lib: remove error checking for debugfs_create_dir()	2023-08-18 10:18:55 -07:00
notifier-error-inject.h
objagg.c
objpool.c	lib: objpool: fix head overrun on RK3588 SBC	2023-12-01 14:53:55 +09:00
of-reconfig-notifier-error-inject.c
oid_registry.c	lib/oid_registry.c: remove redundant assignment to variable num	2022-11-18 13:55:06 -08:00
once.c
overflow_kunit.c	overflow: Replace fake root_device with kunit_device	2023-12-18 13:28:08 -07:00
packing.c	lib: packing: remove MODULE_LICENSE in non-modules	2023-03-09 23:08:04 -08:00
parman.c
parser.c	lib: parser: update documentation for match_NUMBER functions	2023-03-02 21:54:22 -08:00
pci_iomap.c
percpu_counter.c	percpu_counter: extend _limited_add() to negative amounts	2023-10-18 14:34:14 -07:00
percpu_test.c
percpu-refcount.c	percpu-refcount: Use call_rcu_hurry() for atomic switch	2022-11-30 13:16:40 -08:00
plist.c
pm-notifier-error-inject.c
polynomial.c
radix-tree.c	radix tree: remove unused variable	2023-08-21 13:07:22 -07:00
radix-tree.h	radix-tree: move declarations to header	2023-06-12 11:31:50 -07:00
random32.c
ratelimit.c
rbtree_test.c
rbtree.c	lib/rbtree: use '+' instead of '|' for setting color.	2023-04-18 16:39:33 -07:00
rcuref.c	locking/atomics: Use atomic_try_cmpxchg_release() to micro-optimize rcuref_put_slowpath()	2023-10-10 10:14:27 +02:00
ref_tracker.c	lib/ref_tracker: remove warnings in case of allocation failure	2023-06-05 15:28:42 -07:00
refcount.c
rhashtable.c	rhashtable: Allow rhashtable to be used from irq-safe contexts	2022-12-09 10:42:56 +00:00
sbitmap.c	sbitmap: remove stale comment in sbq_calc_wake_batch	2024-01-15 07:23:50 -07:00
scatterlist.c	scatterlist: add missing function params to kernel-doc	2023-09-19 13:21:33 -07:00
seq_buf.c	seq_buf: Fix kernel documentation	2024-02-15 12:17:28 -05:00
sg_pool.c
sg_split.c
siphash_kunit.c
siphash.c
slub_kunit.c	linux-kselftest-kunit-next-6.2-rc1	2022-12-12 16:42:57 -08:00
smp_processor_id.c
sort.c
stackdepot.c	stackdepot: use variable size records for non-evictable entries	2024-02-23 17:27:12 -08:00
stackinit_kunit.c	kernel/range: Uplevel the cxl subsystem's range_contains() helper	2023-02-10 17:32:37 -08:00
stmp_device.c
strcat_kunit.c	string: Add Kunit tests for strcat() family	2023-05-16 14:08:02 -07:00
string_helpers.c	lib/string_helpers: string_get_size() now returns characters wrote	2023-09-11 23:59:47 -04:00
string.c	string: Remove strlcpy()	2024-01-19 11:59:11 -08:00
strncpy_from_user.c
strnlen_user.c
strscpy_kunit.c
syscall.c
test_bitmap.c	bitmap: add test for bitmap_*_region() functions	2023-10-14 20:25:22 -07:00
test_bitops.c
test_bits.c
test_blackhole_dev.c
test_bpf.c	test_bpf: Rename second ALU64_SMOD_X to ALU64_SMOD_K	2023-12-09 21:27:54 -08:00
test_debug_virtual.c
test_dynamic_debug.c
test_firmware.c	firmware_loader: Expand Firmware upload error codes with firmware invalid error	2023-11-24 18:09:19 -08:00
test_fprobe.c	fprobe: Pass return address to the handlers	2023-06-06 21:39:55 +09:00
test_fpu.c
test_free_pages.c
test_hash.c
test_hexdump.c	treewide: use get_random_u32_inclusive() when possible	2022-11-18 02:18:02 +01:00
test_hmm_uapi.h
test_hmm.c	lib: replace kmap() with kmap_local_page()	2023-08-18 10:18:50 -07:00
test_ida.c	Quite a lot of kexec work this time around. Many singleton patches in	2024-01-09 11:46:20 -08:00
test_kmod.c	test_kmod: stop kernel-doc warnings	2023-01-25 14:07:21 -08:00
test_kprobes.c	test_kprobes: Add recursed kprobe test case	2023-02-21 08:52:42 +09:00
test_linear_ranges.c
test_list_sort.c
test_lockup.c
test_maple_tree.c	maple_tree: don't find node end in mtree_lookup_walk()	2023-12-12 10:56:59 -08:00
test_memcat_p.c
test_meminit.c	mm, treewide: introduce NR_PAGE_ORDERS	2024-01-08 15:27:15 -08:00
test_min_heap.c
test_module.c
test_objagg.c
test_objpool.c	lib: test_objpool: make global variables static	2023-11-10 19:59:04 +09:00
test_parman.c
test_printf.c	lib/vsprintf: declare no_hash_pointers in sprintf.h	2023-08-21 13:46:24 -07:00
test_ref_tracker.c	lib/ref_tracker: improve printing stats	2023-06-05 15:28:42 -07:00
test_rhashtable.c	Kill sched.h dependency on rcupdate.h	2023-12-27 11:50:20 -05:00
test_scanf.c	lib: test_scanf: Add explicit type cast to result initialization in test_number_prefix()	2023-08-16 11:47:29 +02:00
test_sort.c
test_static_key_base.c
test_static_keys.c
test_string.c
test_sysctl.c	sysctl: Remove the now superfluous sentinel elements from ctl_table array	2023-12-28 04:57:57 -08:00
test_ubsan.c
test_user_copy.c
test_uuid.c
test_vmalloc.c	lib/test_vmalloc.c: avoid garbage in page array	2023-06-12 11:31:51 -07:00
test_xarray.c
test-kstrtox.c
test-string_helpers.c	lib/test-string_helpers: replace UNESCAPE_ANY by UNESCAPE_ALL_MASK	2023-04-08 13:45:39 -07:00
textsearch.c
timerqueue.c
trace_readwrite.c	lib/trace_readwrite.c:: replace asm-generic/io with linux/io	2023-12-29 12:22:29 -08:00
ts_bm.c	lib/ts_bm: add helper to reduce indentation and improve readability	2023-07-27 13:45:51 +02:00
ts_fsm.c
ts_kmp.c
ubsan.c	UBSAN: use the kernel panic message markers	2023-12-20 14:48:14 -08:00
ubsan.h	ubsan: add prototypes for internal functions	2023-05-30 16:42:01 -07:00
ucmpdi2.c
ucs2_string.c	lib/ucs2_string: Add UCS-2 strscpy function	2023-09-13 10:18:42 -07:00
usercopy.c	uaccess: Add speculation barrier to copy_from_user()	2023-02-21 14:45:22 -08:00
uuid.c
vsprintf.c	lib/vsprintf: Fix %pfwf when current node refcount == 0	2023-12-06 11:06:59 +01:00
win_minmax.c	lib/win_minmax: use /* notation for regular comments	2023-01-11 16:14:21 -08:00
xarray.c	xarray: Document necessary flag in alloc functions	2023-09-05 19:01:38 -04:00
xxhash.c