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Drivers under MIT, BSD-17-clause, or uncle-Bob's-newest-take-on-PD are
all fine, not just GPL.
Signed-off-by: Adam Borowski <kilobyte@angband.pl>
[jc: fixed conflict and refilled paragraph]
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The networking maintainer keeps a public list of the patches being
queued up for the next round of stable releases. Be sure to check there
before asking for a patch to be applied so that you do not waste
people's time.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Translate this commit to Korean:
f77af637f29d ("doc:process: add links where missing")
Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Transalte this commit to Korean:
9799445af124 ("docs: tidy up TOCs and refs to license-rules.rst")
Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Translate this commit to Korean:
dad051395413 ("Documentation/process/howto.rst: add a missing cross-reference")
Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Translate this commit to Korean:
bcd3cf0855c5 ("Documentation/process/howto: Remove outdated info about bugzilla mailing lists")
Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Translate this commit to Korean:
bc0ef4a7e4c3 ("Documentation: Delete reference to the kernel-mentors mailing list")
Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Recently, Free Electrons was renamed to Bootlin[1]. Less recently, the
Linux Cross Reference (LXR) at lxr.free-electrons.com was replaced by
Elixir[2], and lxr.free-electrons.com redirected first to
elixir.free-electrons.com and now to elixir.bootlin.com.
[1]: https://bootlin.com/blog/free-electrons-becomes-bootlin/
[2]: https://github.com/free-electrons/elixir
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Martin Kepplinger <martin.kepplinger@ginzinger.com>
Acked-by: Federico Vaga <federico.vaga@vaga.pv.it>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
sphinx emits warning
WARNING: undefined label: memory-allocation ...
This seems to be caused by the use of a hyphen in the label name instead
of an underscore. Using an underscore for the label name and the
reference clears the warning.
Use underscore not hyphen in label and reference.
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
sphinx emits warning
WARNING: Inline emphasis start-string without end-string.
This is caused by a missing colon.
Add missing colon, clearing shpinx build warning.
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
There is a minor typo in SLUB documentation.
Fix typo.
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
(1) The command to generate man pages is truncated in the pdf version
of the document. Reformat the command into multiple lines to prevent
the truncation.
(2) Older versions of git do not support all variants of pathspec
syntax. Provide commands to generate man pages for various
alternate syntax.
Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This patch fixes two typos, a missing "e" and dma-api/driver_filter was
incorrectly typed dma-api/driver-filter.
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
[jc: fixed obvious language typos on the way in]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Convert scaling document into reStructuredText and add reference to
scaling document into main table of contents in network documentation.
There are no semantic changes.
There are no references to "scaling.txt" file. Whole kernel tree was
checked using:
$ grep -r "scaling\.txt"
Signed-off-by: Otto Sabart <ottosabart@seberm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
There has been some confusion since checkpatch started warning about bool
use in structures, and people have been avoiding using it.
Many people feel there is still a legitimate place for bool in structures,
so provide some guidance on bool usage derived from the entire thread that
spawned the checkpatch warning.
Link: https://lkml.kernel.org/r/CA+55aFwVZk1OfB9T2v014PTAKFhtVan_Zj2dOjnCy3x6E4UJfA@mail.gmail.com
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Joe Perches <joe@perches.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Joey Pabalinas <joeypabalinas@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Keep consistent the document. In the document, option references
are always linked, except for the one I fixed with this patch
Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
It aligns the italian translation with the latest changes:
ae67ee6c5e1d docs: fix Co-Developed-by docs
3fe5dbfef47e Documentation/process/coding-style.rst: don't use "extern" with function prototypes
Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The link referred by the note can't be retrieved: this patch just
remove that old note.
Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The ability to add kerneldoc comments for fields in embedded structures is
useful, but it brought along a whole bunch of warnings for fields that
could not be described before. In many cases, there's little value in
adding docs for these nested fields, and in cases like:
struct a {
struct b {
int c;
} d, e;
};
"c" would have to be described twice (as d.c and e.c) to make the warnings
go away.
We can no doubt do something smarter, but simply suppressing the warnings
for this case removes about 70 warnings from the docs build, freeing us to
focus on the ones that matter more. So make kerneldoc be silent about
missing descriptions for any field containing a ".".
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The SuperH boot code files use a magic format for the SPDX identifier
comment:
LIST "SPDX-License-Identifier: .... "
The trailing quotation mark is not stripped before the token parser is
invoked and causes the scan to fail. Handle it gracefully.
Fixes: 6a0abce4c4cc ("sh: include: convert to SPDX identifiers")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Simon Horman <horms+renesas@verge.net.au>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
A recent commit added SPDX identifiers to the SuperH low level library code
which originates from GCC. This code is licensed under the GPL 2.0 or later
with the GCC runtime library exception.
Unfortunately the authors did not bother to add the exception text to the
LICENSES directory so spdxcheck fails with:
arch/sh/lib/ashiftrt.S: 1:42 Invalid Exception ID: GCC-exception-2.0
arch/sh/lib/ashlsi3.S: 1:42 Invalid Exception ID: GCC-exception-2.0
arch/sh/lib/ashrsi3.S: 1:42 Invalid Exception ID: GCC-exception-2.0
arch/sh/lib/lshrsi3.S: 1:42 Invalid Exception ID: GCC-exception-2.0
arch/sh/lib/movmem.S: 1:42 Invalid Exception ID: GCC-exception-2.0
arch/sh/lib/udiv_qrnnd.S: 1:42 Invalid Exception ID: GCC-exception-2.0
arch/sh/lib/udivsi3.S: 1:42 Invalid Exception ID: GCC-exception-2.0
arch/sh/lib/udivsi3_i4i-Os.S: 1:42 Invalid Exception ID: GCC-exception-2.0
arch/sh/lib/udivsi3_i4i.S: 1:42 Invalid Exception ID: GCC-exception-2.0
Add the exception text along with the required tags which allow automated
checking.
Fixes: 4494ce4fb4ff ("sh: lib: convert to SPDX identifiers")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Simon Horman <horms+renesas@verge.net.au>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
We don't do page cache reparent anymore when offlining memcg, so update
force empty related content accordingly.
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Neither file contains any kerneldoc comments, so including them generates
these warnings in the docs build:
./include/linux/rcupdate_wait.h:1: warning: no structured comments found
./include/linux/rcutree.h:1: warning: no structured comments found
Remove them and make life a little quieter.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
While using this guide to learn the new documentation method, I saw
a few phrases that I felt could be improved. These small changes
improve the grammar and choice of words to further enhance the
installation instructions.
Signed-off-by: Joel Nider <joeln@il.ibm.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Fix the mismatch between "Useful GFP flag combinations" section naming in
the DOC: section in include/linux/gfp.h and
Documentation/core-api/mm-api.rst. This brings in the documentation,
and eliminates one warning:
./include/linux/gfp.h:1: warning: no structured comments found
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
[jc: tweaked changelog]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Mention that when a part of a slab cache might be exported to the
userspace, the cache should be created using kmem_cache_create_usercopy()
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
svn commit 231296 matches commit d29e939c63b71 ("Add fuzzing coverage
support") in the gcc git. The change is part of gcc 6.1.0.
Replace the svn commit number with a gcc version which everyone can
easily compare.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Bits are usually numbered starting from zero, so 4 should be bit 2, not
bit 3.
Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This adds a simple sample program mounting binderfs and adding, then
removing a binder device. Hopefully, it will be helpful to users who want
to know how binderfs is supposed to be used.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This documents the Android binderfs filesystem used to dynamically add and
remove binder devices that are private to each instance.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
[jc: tweaked markup and added to filesystems/index.rst]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Fix Sphinx warnings in ibmvmc.rst, add an index.rst file in
Documentation/misc-devices/, and insert that index file into the
top-level index file.
Documentation/misc-devices/ibmvmc.rst:2: WARNING: Explicit markup ends without a blank line; unexpected unindent.
Documentation/misc-devices/ibmvmc.rst:: WARNING: document isn't included in any toctree
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Steven Royer <seroyer@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Fix Sphinx warning in coding-style.rst:
Documentation/process/coding-style.rst:446: WARNING: Inline interpreted text or phrase reference start-string without end-string.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Add a section about decoding /proc/sys/kernel/tainted, create a more
understandable intro and a hopefully explain better the tainted flags in
bugs, oops or panics messages. Only thing missing then is a table that
quickly describes the various bits and taint flags before going into more
detail, so add that as well.
That table is partly based on a section from Documentation/sysctl/kernel.txt,
but a bit more compact. To avoid confusion I added the shortened version to
kernel.txt; the same table is used in three different places now:
./tools/debugging/kernel-chktaint,
Documentation/admin-guide/tainted-kernels.rst and
Documentation/sysctl/kernel.txt
During review of v1 (see above) a number of existing issues with the text
were raised, like outdated usages as well as incomplete or missing
descriptions. Address most of those as well.
Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info>
[jc: tightened up changelog]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Add a script to the tools/ directory that shows if or why the running
kernel was tainted. The script was mostly written by Randy Dunlap; I
enhanced the script a bit. There does not appear to be a good home for
this script. so create tools/debugging for tools of this nature.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info>
[ jc: fixed conflicts, rewrote changelog ]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
It translats the document process/submitting-patches.rst.
Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
In emacs 23.1 support for directory-local variables was added (see also
https://lists.gnu.org/archive/html/info-gnu-emacs/2009-07/msg00000.html).
Simplify the settings in coding-style.rst by using that feature.
Additionally, do not inherit any settings from emacs' linux coding style
to minimize dependencies on the version of emacs that is being used.
I have verified with several large and nontrivial kernel source files
that the new settings format code according to what checkpatch expects.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Alison Chaiken <alison@she-devel.com>
Cc: Joe Perches <joe@perches.com>
Cc: Federico Vaga <federico.vaga@vaga.pv.it>
Cc: Geyslan G. Bem <geyslan@gmail.com>
Cc: Tiago Natel de Moura <tiago4orion@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This patch just adds references to offload documents into main table of
contents in network documentation.
Signed-off-by: Otto Sabart <ottosabart@seberm.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The titles do not look very nice in the table of contents generated by
Sphinx.
I also think it is obvious that the documents are describing offloads
in the Linux Networking Stack.
Signed-off-by: Otto Sabart <ottosabart@seberm.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This patch renames offload files. This is necessary for Sphinx.
Also update reference to checksum-offloads.rst file.
Whole kernel code was grepped for references using:
$ grep -r "\(segmentation\|checksum\)-offloads.txt" .
There should be no other references
to {segmentation,checksum}-offloads.txt files.
Signed-off-by: Otto Sabart <ottosabart@seberm.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Add small number of markups which are sufficient for conversion
into reStructuredText.
Unfortunately there was necessary to restructure all sections
in checksum-offloads.txt file and create paragraphs separated
by newline. There also must not be a space at the
beginning of paragpraph.
There are no semantic changes.
Signed-off-by: Otto Sabart <ottosabart@seberm.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Fix Sphinx warnings in path-lookup.rst:
Documentation/filesystems/path-lookup.rst:347: WARNING: Title underline too short.
Documentation/filesystems/path-lookup.rst:358: WARNING: Title underline too short.
[...]
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
- improve boolinit.cocci and use_after_iter.cocci semantic patches
- fix alignment for kallsyms
- move 'asm goto' compiler test to Kconfig and clean up jump_label
CONFIG option
- generate asm-generic wrappers automatically if arch does not implement
mandatory UAPI headers
- remove redundant generic-y defines
- misc cleanups
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Merge tag 'kbuild-v4.21-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull more Kbuild updates from Masahiro Yamada:
- improve boolinit.cocci and use_after_iter.cocci semantic patches
- fix alignment for kallsyms
- move 'asm goto' compiler test to Kconfig and clean up jump_label
CONFIG option
- generate asm-generic wrappers automatically if arch does not
implement mandatory UAPI headers
- remove redundant generic-y defines
- misc cleanups
* tag 'kbuild-v4.21-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kconfig: rename generated .*conf-cfg to *conf-cfg
kbuild: remove unnecessary stubs for archheader and archscripts
kbuild: use assignment instead of define ... endef for filechk_* rules
arch: remove redundant UAPI generic-y defines
kbuild: generate asm-generic wrappers if mandatory headers are missing
arch: remove stale comments "UAPI Header export list"
riscv: remove redundant kernel-space generic-y
kbuild: change filechk to surround the given command with { }
kbuild: remove redundant target cleaning on failure
kbuild: clean up rule_dtc_dt_yaml
kbuild: remove UIMAGE_IN and UIMAGE_OUT
jump_label: move 'asm goto' support test to Kconfig
kallsyms: lower alignment on ARM
scripts: coccinelle: boolinit: drop warnings on named constants
scripts: coccinelle: check for redeclaration
kconfig: remove unused "file" field of yylval union
nds32: remove redundant kernel-space generic-y
nios2: remove unneeded HAS_DMA define
Pull perf tooling updates form Ingo Molnar:
"A final batch of perf tooling changes: mostly fixes and small
improvements"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (29 commits)
perf session: Add comment for perf_session__register_idle_thread()
perf thread-stack: Fix thread stack processing for the idle task
perf thread-stack: Allocate an array of thread stacks
perf thread-stack: Factor out thread_stack__init()
perf thread-stack: Allow for a thread stack array
perf thread-stack: Avoid direct reference to the thread's stack
perf thread-stack: Tidy thread_stack__bottom() usage
perf thread-stack: Simplify some code in thread_stack__process()
tools gpio: Allow overriding CFLAGS
tools power turbostat: Override CFLAGS assignments and add LDFLAGS to build command
tools thermal tmon: Allow overriding CFLAGS assignments
tools power x86_energy_perf_policy: Override CFLAGS assignments and add LDFLAGS to build command
perf c2c: Increase the HITM ratio limit for displayed cachelines
perf c2c: Change the default coalesce setup
perf trace beauty ioctl: Beautify USBDEVFS_ commands
perf trace beauty: Export function to get the files for a thread
perf trace: Wire up ioctl's USBDEBFS_ cmd table generator
perf beauty ioctl: Add generator for USBDEVFS_ ioctl commands
tools headers uapi: Grab a copy of usbdevice_fs.h
perf trace: Store the major number for a file when storing its pathname
...
The semantics of what "in core" means for the mincore() system call are
somewhat unclear, but Linux has always (since 2.3.52, which is when
mincore() was initially done) treated it as "page is available in page
cache" rather than "page is mapped in the mapping".
The problem with that traditional semantic is that it exposes a lot of
system cache state that it really probably shouldn't, and that users
shouldn't really even care about.
So let's try to avoid that information leak by simply changing the
semantics to be that mincore() counts actual mapped pages, not pages
that might be cheaply mapped if they were faulted (note the "might be"
part of the old semantics: being in the cache doesn't actually guarantee
that you can access them without IO anyway, since things like network
filesystems may have to revalidate the cache before use).
In many ways the old semantics were somewhat insane even aside from the
information leak issue. From the very beginning (and that beginning is
a long time ago: 2.3.52 was released in March 2000, I think), the code
had a comment saying
Later we can get more picky about what "in core" means precisely.
and this is that "later". Admittedly it is much later than is really
comfortable.
NOTE! This is a real semantic change, and it is for example known to
change the output of "fincore", since that program literally does a
mmmap without populating it, and then doing "mincore()" on that mapping
that doesn't actually have any pages in it.
I'm hoping that nobody actually has any workflow that cares, and the
info leak is real.
We may have to do something different if it turns out that people have
valid reasons to want the old semantics, and if we can limit the
information leak sanely.
Cc: Kevin Easton <kevin@guarana.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Masatake YAMATO <yamato@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 594cc251fdd0 ("make 'user_access_begin()' do 'access_ok()'")
broke both alpha and SH booting in qemu, as noticed by Guenter Roeck.
It turns out that the bug wasn't actually in that commit itself (which
would have been surprising: it was mostly a no-op), but in how the
addition of access_ok() to the strncpy_from_user() and strnlen_user()
functions now triggered the case where those functions would test the
access of the very last byte of the user address space.
The string functions actually did that user range test before too, but
they did it manually by just comparing against user_addr_max(). But
with user_access_begin() doing the check (using "access_ok()"), it now
exposed problems in the architecture implementations of that function.
For example, on alpha, the access_ok() helper macro looked like this:
#define __access_ok(addr, size) \
((get_fs().seg & (addr | size | (addr+size))) == 0)
and what it basically tests is of any of the high bits get set (the
USER_DS masking value is 0xfffffc0000000000).
And that's completely wrong for the "addr+size" check. Because it's
off-by-one for the case where we check to the very end of the user
address space, which is exactly what the strn*_user() functions do.
Why? Because "addr+size" will be exactly the size of the address space,
so trying to access the last byte of the user address space will fail
the __access_ok() check, even though it shouldn't. As a result, the
user string accessor functions failed consistently - because they
literally don't know how long the string is going to be, and the max
access is going to be that last byte of the user address space.
Side note: that alpha macro is buggy for another reason too - it re-uses
the arguments twice.
And SH has another version of almost the exact same bug:
#define __addr_ok(addr) \
((unsigned long __force)(addr) < current_thread_info()->addr_limit.seg)
so far so good: yes, a user address must be below the limit. But then:
#define __access_ok(addr, size) \
(__addr_ok((addr) + (size)))
is wrong with the exact same off-by-one case: the case when "addr+size"
is exactly _equal_ to the limit is actually perfectly fine (think "one
byte access at the last address of the user address space")
The SH version is actually seriously buggy in another way: it doesn't
actually check for overflow, even though it did copy the _comment_ that
talks about overflow.
So it turns out that both SH and alpha actually have completely buggy
implementations of access_ok(), but they happened to work in practice
(although the SH overflow one is a serious serious security bug, not
that anybody likely cares about SH security).
This fixes the problems by using a similar macro on both alpha and SH.
It isn't trying to be clever, the end address is based on this logic:
unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b;
which basically says "add start and length, and then subtract one unless
the length was zero". We can't subtract one for a zero length, or we'd
just hit an underflow instead.
For a lot of access_ok() users the length is a constant, so this isn't
actually as expensive as it initially looks.
Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
