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Peter Collingbourne 758cabae31 kasan: test: add memcpy test that avoids out-of-bounds write 
With HW tag-based KASAN, error checks are performed implicitly by the
load and store instructions in the memcpy implementation.  A failed
check results in tag checks being disabled and execution will keep
going.  As a result, under HW tag-based KASAN, prior to commit
1b0668be62 ("kasan: test: disable kmalloc_memmove_invalid_size for
HW_TAGS"), this memcpy would end up corrupting memory until it hits an
inaccessible page and causes a kernel panic.

This is a pre-existing issue that was revealed by commit 285133040e
("arm64: Import latest memcpy()/memmove() implementation") which changed
the memcpy implementation from using signed comparisons (incorrectly,
resulting in the memcpy being terminated early for negative sizes) to
using unsigned comparisons.

It is unclear how this could be handled by memcpy itself in a reasonable
way.  One possibility would be to add an exception handler that would
force memcpy to return if a tag check fault is detected -- this would
make the behavior roughly similar to generic and SW tag-based KASAN.
However, this wouldn't solve the problem for asynchronous mode and also
makes memcpy behavior inconsistent with manually copying data.

This test was added as a part of a series that taught KASAN to detect
negative sizes in memory operations, see commit 8cceeff48f ("kasan:
detect negative size in memory operation function").  Therefore we
should keep testing for negative sizes with generic and SW tag-based
KASAN.  But there is some value in testing small memcpy overflows, so
let's add another test with memcpy that does not destabilize the kernel
by performing out-of-bounds writes, and run it in all modes.

Link: https://linux-review.googlesource.com/id/I048d1e6a9aff766c4a53f989fb0c83de68923882
Link: https://lkml.kernel.org/r/20210910211356.3603758-1-pcc@google.com
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Evgenii Stepanov <eugenis@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>
2021-11-06 13:30:33 -07:00
arch * Fixes for s390 interrupt delivery 2021-10-31 11:19:02 -07:00
block block-5.15-2021-10-29 2021-10-29 11:10:29 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-08-30 12:57:10 -07:00
Documentation Networking fixes for 5.15-rc8/final, including fixes from WiFi 2021-10-28 10:17:31 -07:00
drivers mm: move kvmalloc-related functions to slab.h 2021-11-06 13:30:32 -07:00
fs d_path: fix Kernel doc validator complaining 2021-11-06 13:30:32 -07:00
include kasan: generic: introduce kasan_record_aux_stack_noalloc() 2021-11-06 13:30:33 -07:00
init mm: disable NUMA_BALANCING_DEFAULT_ENABLED and TRANSPARENT_HUGEPAGE on PREEMPT_RT 2021-11-06 13:30:33 -07:00
ipc ipc: remove memcg accounting for sops objects in do_semtimedop() 2021-09-14 10:22:11 -07:00
kernel workqueue, kasan: avoid alloc_pages() when recording stack 2021-11-06 13:30:33 -07:00
lib kasan: test: add memcpy test that avoids out-of-bounds write 2021-11-06 13:30:33 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm kasan: fix tag for large allocations when using CONFIG_SLAB 2021-11-06 13:30:33 -07:00
net mptcp: fix corrupt receiver key in MPC + data + checksum 2021-10-28 08:19:06 -07:00
samples samples/bpf: Relicense bpf_insn.h as GPL-2.0-only OR BSD-2-Clause 2021-09-29 16:03:55 +02:00
scripts scripts/decodecode: fix faulting instruction no print when opps.file is DOS format 2021-11-06 13:30:32 -07:00
security Merge branch 'ucount-fixes-for-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2021-10-21 17:27:17 -10:00
sound ALSA: usb-audio: Fix microphone sound on Jieli webcam. 2021-10-19 08:07:01 +02:00
tools perf script: Fix PERF_SAMPLE_WEIGHT_STRUCT support 2021-10-31 12:51:41 -03:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Remove tlbs_dirty 2021-09-23 11:01:12 -04:00
.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 drm fixes for 5.15 final 2021-10-28 12:17:01 -07:00
Makefile Linux 5.15 2021-10-31 13:53:10 -07:00
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.