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The source for the Linux kernel used in Windows Subsystem for Linux 2 (WSL2)
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Kees Cook ff41804632 Compiler Attributes: add __alloc_size() for better bounds checking 
[ Upstream commit 86cffecdea ]

GCC and Clang can use the "alloc_size" attribute to better inform the
results of __builtin_object_size() (for compile-time constant values).
Clang can additionally use alloc_size to inform the results of
__builtin_dynamic_object_size() (for run-time values).

Because GCC sees the frequent use of struct_size() as an allocator size
argument, and notices it can return SIZE_MAX (the overflow indication),
it complains about these call sites overflowing (since SIZE_MAX is
greater than the default -Walloc-size-larger-than=PTRDIFF_MAX).  This
isn't helpful since we already know a SIZE_MAX will be caught at
run-time (this was an intentional design).  To deal with this, we must
disable this check as it is both a false positive and redundant.  (Clang
does not have this warning option.)

Unfortunately, just checking the -Wno-alloc-size-larger-than is not
sufficient to make the __alloc_size attribute behave correctly under
older GCC versions.  The attribute itself must be disabled in those
situations too, as there appears to be no way to reliably silence the
SIZE_MAX constant expression cases for GCC versions less than 9.1:

   In file included from ./include/linux/resource_ext.h:11,
                    from ./include/linux/pci.h:40,
                    from drivers/net/ethernet/intel/ixgbe/ixgbe.h:9,
                    from drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c:4:
   In function 'kmalloc_node',
       inlined from 'ixgbe_alloc_q_vector' at ./include/linux/slab.h:743:9:
   ./include/linux/slab.h:618:9: error: argument 1 value '18446744073709551615' exceeds maximum object size 9223372036854775807 [-Werror=alloc-size-larger-than=]
     return __kmalloc_node(size, flags, node);
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   ./include/linux/slab.h: In function 'ixgbe_alloc_q_vector':
   ./include/linux/slab.h:455:7: note: in a call to allocation function '__kmalloc_node' declared here
    void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_slab_alignment __malloc;
          ^~~~~~~~~~~~~~

Specifically:
 '-Wno-alloc-size-larger-than' is not correctly handled by GCC < 9.1
    https://godbolt.org/z/hqsfG7q84 (doesn't disable)
    https://godbolt.org/z/P9jdrPTYh (doesn't admit to not knowing about option)
    https://godbolt.org/z/465TPMWKb (only warns when other warnings appear)

 '-Walloc-size-larger-than=18446744073709551615' is not handled by GCC < 8.2
    https://godbolt.org/z/73hh1EPxz (ignores numeric value)

Since anything marked with __alloc_size would also qualify for marking
with __malloc, just include __malloc along with it to avoid redundant
markings.  (Suggested by Linus Torvalds.)

Finally, make sure checkpatch.pl doesn't get confused about finding the
__alloc_size attribute on functions.  (Thanks to Joe Perches.)

Link: https://lkml.kernel.org/r/20210930222704.2631604-3-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexandre Bounine <alex.bou9@gmail.com>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jing Xiangfeng <jingxiangfeng@huawei.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2022-07-12 16:35:01 +02:00
Documentation docs: update mapping documentation 2022-07-02 16:41:15 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
arch riscv/mm: Add XIP_FIXUP for riscv_pfn_base 2022-07-12 16:35:01 +02:00
block block: fix rq-qos breakage from skipping rq_qos_done_bio() 2022-07-12 16:34:57 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: memneq - move into lib/ 2022-06-22 14:22:03 +02:00
drivers mtd: spi-nor: Skip erase logic when SPI_NOR_NO_ERASE is set 2022-07-12 16:35:01 +02:00
fs NFSD: COMMIT operations must not return NFS?ERR_INVAL 2022-07-12 16:35:01 +02:00
include Compiler Attributes: add __alloc_size() for better bounds checking 2022-07-12 16:35:01 +02:00
init Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug 2022-06-09 10:23:26 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:23:10 +02:00
kernel bpf: Stop caching subprog index in the bpf_pseudo_func insn 2022-07-12 16:34:54 +02:00
lib crypto: memneq - move into lib/ 2022-06-22 14:22:03 +02:00
mm mm/filemap: fix UAF in find_lock_entries 2022-07-12 16:34:47 +02:00
net batman-adv: Use netif_rx(). 2022-07-12 16:35:01 +02:00
samples samples/landlock: Format with clang-format 2022-06-09 10:23:23 +02:00
scripts Compiler Attributes: add __alloc_size() for better bounds checking 2022-07-12 16:35:01 +02:00
security fs: support mapped mounts of mapped filesystems 2022-07-02 16:41:17 +02:00
sound ASoC: rt5682: Fix deadlock on resume 2022-07-12 16:34:55 +02:00
tools Revert "selftests/bpf: Add test for bpf_timer overwriting crash" 2022-07-12 16:34:47 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: avoid NULL pointer dereference in kvm_dirty_ring_push 2022-04-13 20:59:26 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
…
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Input: goodix - add a goodix.h header file 2022-07-12 16:34:51 +02:00
Makefile Compiler Attributes: add __alloc_size() for better bounds checking 2022-07-12 16:35:01 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.