kernel/linux.git/lib/test_kasan.c, branch v5.4.107

kasan: stop tests being eliminated as dead code with FORTIFY_SOURCE

2020-06-22T07:31:12+00:00

[ Upstream commit adb72ae1915db28f934e9e02c18bfcea2f3ed3b7 ] Patch series "Fix some incompatibilites between KASAN and FORTIFY_SOURCE", v4. 3 KASAN self-tests fail on a kernel with both KASAN and FORTIFY_SOURCE: memchr, memcmp and strlen. When FORTIFY_SOURCE is on, a number of functions are replaced with fortified versions, which attempt to check the sizes of the operands. However, these functions often directly invoke __builtin_foo() once they have performed the fortify check. The compiler can detect that the results of these functions are not used, and knows that they have no other side effects, and so can eliminate them as dead code. Why are only memchr, memcmp and strlen affected? ================================================ Of string and string-like functions, kasan_test tests: * strchr -> not affected, no fortified version * strrchr -> likewise * strcmp -> likewise * strncmp -> likewise * strnlen -> not affected, the fortify source implementation calls the underlying strnlen implementation which is instrumented, not a builtin * strlen -> affected, the fortify souce implementation calls a __builtin version which the compiler can determine is dead. * memchr -> likewise * memcmp -> likewise * memset -> not affected, the compiler knows that memset writes to its first argument and therefore is not dead. Why does this not affect the functions normally? ================================================ In string.h, these functions are not marked as __pure, so the compiler cannot know that they do not have side effects. If relevant functions are marked as __pure in string.h, we see the following warnings and the functions are elided: lib/test_kasan.c: In function `kasan_memchr': lib/test_kasan.c:606:2: warning: statement with no effect [-Wunused-value] memchr(ptr, '1', size + 1); ^~~~~~~~~~~~~~~~~~~~~~~~~~ lib/test_kasan.c: In function `kasan_memcmp': lib/test_kasan.c:622:2: warning: statement with no effect [-Wunused-value] memcmp(ptr, arr, size+1); ^~~~~~~~~~~~~~~~~~~~~~~~ lib/test_kasan.c: In function `kasan_strings': lib/test_kasan.c:645:2: warning: statement with no effect [-Wunused-value] strchr(ptr, '1'); ^~~~~~~~~~~~~~~~ ... This annotation would make sense to add and could be added at any point, so the behaviour of test_kasan.c should change. The fix ======= Make all the functions that are pure write their results to a global, which makes them live. The strlen and memchr tests now pass. The memcmp test still fails to trigger, which is addressed in the next patch. [dja@axtens.net: drop patch 3] Link: http://lkml.kernel.org/r/20200424145521.8203-2-dja@axtens.net Fixes: 0c96350a2d2f ("lib/test_kasan.c: add tests for several string/memory API functions") Signed-off-by: Daniel Axtens Signed-off-by: Andrew Morton Tested-by: David Gow Reviewed-by: Dmitry Vyukov Cc: Daniel Micay Cc: Andrey Ryabinin Cc: Alexander Potapenko Link: http://lkml.kernel.org/r/20200423154503.5103-1-dja@axtens.net Link: http://lkml.kernel.org/r/20200423154503.5103-2-dja@axtens.net Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

lib/test_kasan.c: fix memory leak in kmalloc_oob_krealloc_more()

2020-02-11T12:35:14+00:00

commit 3e21d9a501bf99aee2e5835d7f34d8c823f115b5 upstream. In case memory resources for _ptr2_ were allocated, release them before return. Notice that in case _ptr1_ happens to be NULL, krealloc() behaves exactly like kmalloc(). Addresses-Coverity-ID: 1490594 ("Resource leak") Link: http://lkml.kernel.org/r/20200123160115.GA4202@embeddedor Fixes: 3f15801cdc23 ("lib: add kasan test module") Signed-off-by: Gustavo A. R. Silva Reviewed-by: Dmitry Vyukov Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

lib/test_kasan.c: add roundtrip tests

2019-09-24T22:54:08+00:00

In several places we need to be able to operate on pointers which have gone via a roundtrip: virt -> {phys,page} -> virt With KASAN_SW_TAGS, we can't preserve the tag for SLUB objects, and the {phys,page} -> virt conversion will use KASAN_TAG_KERNEL. This patch adds tests to ensure that this works as expected, without false positives which have recently been spotted [1,2] in testing. [1] https://lore.kernel.org/linux-arm-kernel/20190819114420.2535-1-walter-zh.wu@mediatek.com/ [2] https://lore.kernel.org/linux-arm-kernel/20190819132347.GB9927@lakrids.cambridge.arm.com/ [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20190821153927.28630-1-mark.rutland@arm.com Signed-off-by: Mark Rutland Reviewed-by: Andrey Konovalov Tested-by: Andrey Konovalov Acked-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/test_kasan: Add test for double-kzfree detection

2019-07-12T18:05:42+00:00

Add a simple test that checks if double-kzfree is being detected correctly. Link: http://lkml.kernel.org/r/20190626142014.141844-4-elver@google.com Signed-off-by: Marco Elver Reviewed-by: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Mark Rutland Cc: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/test_kasan: add bitops tests

2019-07-12T18:05:42+00:00

Patch series "Bitops instrumentation for KASAN", v5. This patch (of 3): This adds bitops tests to the test_kasan module. In a follow-up patch, support for bitops instrumentation will be added. Link: http://lkml.kernel.org/r/20190613125950.197667-2-elver@google.com Signed-off-by: Marco Elver Acked-by: Mark Rutland Reviewed-by: Andrey Ryabinin Cc: Peter Zijlstra (Intel) Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: "H. Peter Anvin" Cc: Jonathan Corbet Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Arnd Bergmann Cc: Josh Poimboeuf Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55+00:00

Based on 2 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Enrico Weigelt Reviewed-by: Kate Stewart Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman

kasan: remove use after scope bugs detection.

2019-03-06T05:07:13+00:00

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

2018-10-26T23:25:18+00:00

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

2018-04-11T17:28:32+00:00

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'

2018-02-07T02:32:43+00:00

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