kernel/lib/test_kasan.c, branch linux-5.1.y

kasan: remove use after scope bugs detection.

2019-03-06T05:07:13Z

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 Acked-by: Will Deacon [arm64] Cc: Qian Cai Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Catalin Marinas Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/test_kasan.c: add tests for several string/memory API functions

2018-10-26T23:25:18Z

Arch code may have asm implementation of string/memory API functions instead of using generic one from lib/string.c. KASAN don't see memory accesses in asm code, thus can miss many bugs. E.g. on ARM64 KASAN don't see bugs in memchr(), memcmp(), str[r]chr(), str[n]cmp(), str[n]len(). Add tests for these functions to be sure that we notice the problem on other architectures. Link: http://lkml.kernel.org/r/20180920135631.23833-3-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Ard Biesheuvel Cc: Dmitry Vyukov Cc: Kyeongdon Kim Cc: Mark Rutland Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: fix invalid-free test crashing the kernel

2018-04-11T17:28:32Z

When an invalid-free is triggered by one of the KASAN tests, the object doesn't actually get freed. This later leads to a BUG failure in kmem_cache_destroy that checks that there are no allocated objects in the cache that is being destroyed. Fix this by calling kmem_cache_free with the proper object address after the call that triggers invalid-free. Link: http://lkml.kernel.org/r/286eaefc0a6c3fa9b83b87e7d6dc0fbb5b5c9926.1519924383.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Acked-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Geert Uytterhoeven Cc: Nick Terrell Cc: Chris Mason Cc: Yury Norov Cc: Al Viro Cc: "Luis R . Rodriguez" Cc: Palmer Dabbelt Cc: "Paul E . McKenney" Cc: Jeff Layton Cc: "Jason A . Donenfeld" Cc: Kostya Serebryany Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: remove redundant initialization of variable 'real_size'

2018-02-07T02:32:43Z

Variable real_size is initialized with a value that is never read, it is re-assigned a new value later on, hence the initialization is redundant and can be removed. Cleans up clang warning: lib/test_kasan.c:422:21: warning: Value stored to 'real_size' during its initialization is never read Link: http://lkml.kernel.org/r/20180206144950.32457-1-colin.king@canonical.com Signed-off-by: Colin Ian King Acked-by: Andrey Ryabinin Reviewed-by: Andrew Morton Cc: Alexander Potapenko Cc: Dmitry Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: detect invalid frees

2018-02-07T02:32:43Z

Detect frees of pointers into middle of heap objects. Link: http://lkml.kernel.org/r/cb569193190356beb018a03bb8d6fbae67e7adbc.1514378558.git.dvyukov@google.com Signed-off-by: Dmitry Vyukov Cc: Andrey Ryabinin a Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: detect invalid frees for large objects

2018-02-07T02:32:42Z

Patch series "kasan: detect invalid frees". KASAN detects double-frees, but does not detect invalid-frees (when a pointer into a middle of heap object is passed to free). We recently had a very unpleasant case in crypto code which freed an inner object inside of a heap allocation. This left unnoticed during free, but totally corrupted heap and later lead to a bunch of random crashes all over kernel code. Detect invalid frees. This patch (of 5): Detect frees of pointers into middle of large heap objects. I dropped const from kasan_kfree_large() because it starts propagating through a bunch of functions in kasan_report.c, slab/slub nearest_obj(), all of their local variables, fixup_red_left(), etc. Link: http://lkml.kernel.org/r/1b45b4fe1d20fc0de1329aab674c1dd973fee723.1514378558.git.dvyukov@google.com Signed-off-by: Dmitry Vyukov Cc: Andrey Ryabinin a Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: add tests for alloca poisoning

2018-02-07T02:32:42Z

Link: http://lkml.kernel.org/r/20171204191735.132544-5-paullawrence@google.com Signed-off-by: Greg Hackmann Signed-off-by: Paul Lawrence Acked-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Masahiro Yamada Cc: Matthias Kaehlcke Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/test: delete five error messages for failed memory allocations

2017-11-18T00:10:01Z

Omit extra messages for a memory allocation failure in these functions. This issue was detected by using the Coccinelle software. Link: http://lkml.kernel.org/r/410a4c5a-4ee0-6fcc-969c-103d8e496b78@users.sourceforge.net Signed-off-by: Markus Elfring Acked-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: report only the first error by default

2017-04-01T00:13:30Z

Disable kasan after the first report. There are several reasons for this: - Single bug quite often has multiple invalid memory accesses causing storm in the dmesg. - Write OOB access might corrupt metadata so the next report will print bogus alloc/free stacktraces. - Reports after the first easily could be not bugs by itself but just side effects of the first one. Given that multiple reports usually only do harm, it makes sense to disable kasan after the first one. If user wants to see all the reports, the boot-time parameter kasan_multi_shot must be used. [aryabinin@virtuozzo.com: wrote changelog and doc, added missing include] Link: http://lkml.kernel.org/r/20170323154416.30257-1-aryabinin@virtuozzo.com Signed-off-by: Mark Rutland Signed-off-by: Andrey Ryabinin Cc: Andrey Konovalov Cc: Alexander Potapenko Cc: Dmitry Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: add memcg kmem_cache test

2017-02-25T01:46:56Z

Make a kasan test which uses a SLAB_ACCOUNT slab cache. If the test is run within a non default memcg, then it uncovers the bug fixed by "kasan: drain quarantine of memcg slab objects"[1]. If run without fix [1] it shows "Slab cache still has objects", and the kmem_cache structure is leaked. Here's an unpatched kernel test: $ dmesg -c > /dev/null $ mkdir /sys/fs/cgroup/memory/test $ echo $$ > /sys/fs/cgroup/memory/test/tasks $ modprobe test_kasan 2> /dev/null $ dmesg | grep -B1 still [ 123.456789] kasan test: memcg_accounted_kmem_cache allocate memcg accounted object [ 124.456789] kmem_cache_destroy test_cache: Slab cache still has objects Kernels with fix [1] don't have the "Slab cache still has objects" warning or the underlying leak. The new test runs and passes in the default (root) memcg, though in the root memcg it won't uncover the problem fixed by [1]. Link: http://lkml.kernel.org/r/1482257462-36948-2-git-send-email-gthelen@google.com Signed-off-by: Greg Thelen Reviewed-by: Vladimir Davydov Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds