diff options
author | Alexander Potapenko <glider@google.com> | 2023-03-03 15:14:31 +0100 |
---|---|---|
committer | Andrew Morton <akpm@linux-foundation.org> | 2023-03-28 16:20:11 -0700 |
commit | d340292553ab48d32d3e768bbb1d11fb942fe02e (patch) | |
tree | 08e9bdb7d3ac0c7554d062808ccf1ffe84cf4774 /mm/kmsan | |
parent | 6dc4bd4e2fe395f8c9d5d0892e45ff7fed5c66f3 (diff) |
kmsan: another take at fixing memcpy tests
commit 5478afc55a21 ("kmsan: fix memcpy tests") uses OPTIMIZER_HIDE_VAR()
to hide the uninitialized var from the compiler optimizations.
However OPTIMIZER_HIDE_VAR(uninit) enforces an immediate check of @uninit,
so memcpy tests did not actually check the behavior of memcpy(), because
they always contained a KMSAN report.
Replace OPTIMIZER_HIDE_VAR() with a file-local macro that just clobbers
the memory with a barrier(), and add a test case for memcpy() that does
not expect an error report.
Also reflow kmsan_test.c with clang-format.
Link: https://lkml.kernel.org/r/20230303141433.3422671-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/kmsan')
-rw-r--r-- | mm/kmsan/kmsan_test.c | 44 |
1 files changed, 38 insertions, 6 deletions
diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c index 088e21a48dc4..aeddfdd4f679 100644 --- a/mm/kmsan/kmsan_test.c +++ b/mm/kmsan/kmsan_test.c @@ -408,6 +408,37 @@ static void test_printk(struct kunit *test) } /* + * Prevent the compiler from optimizing @var away. Without this, Clang may + * notice that @var is uninitialized and drop memcpy() calls that use it. + * + * There is OPTIMIZER_HIDE_VAR() in linux/compier.h that we cannot use here, + * because it is implemented as inline assembly receiving @var as a parameter + * and will enforce a KMSAN check. Same is true for e.g. barrier_data(var). + */ +#define DO_NOT_OPTIMIZE(var) barrier() + +/* + * Test case: ensure that memcpy() correctly copies initialized values. + * Also serves as a regression test to ensure DO_NOT_OPTIMIZE() does not cause + * extra checks. + */ +static void test_init_memcpy(struct kunit *test) +{ + EXPECTATION_NO_REPORT(expect); + volatile int src; + volatile int dst = 0; + + DO_NOT_OPTIMIZE(src); + src = 1; + kunit_info( + test, + "memcpy()ing aligned initialized src to aligned dst (no reports)\n"); + memcpy((void *)&dst, (void *)&src, sizeof(src)); + kmsan_check_memory((void *)&dst, sizeof(dst)); + KUNIT_EXPECT_TRUE(test, report_matches(&expect)); +} + +/* * Test case: ensure that memcpy() correctly copies uninitialized values between * aligned `src` and `dst`. */ @@ -420,7 +451,7 @@ static void test_memcpy_aligned_to_aligned(struct kunit *test) kunit_info( test, "memcpy()ing aligned uninit src to aligned dst (UMR report)\n"); - OPTIMIZER_HIDE_VAR(uninit_src); + DO_NOT_OPTIMIZE(uninit_src); memcpy((void *)&dst, (void *)&uninit_src, sizeof(uninit_src)); kmsan_check_memory((void *)&dst, sizeof(dst)); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); @@ -443,7 +474,7 @@ static void test_memcpy_aligned_to_unaligned(struct kunit *test) kunit_info( test, "memcpy()ing aligned uninit src to unaligned dst (UMR report)\n"); - OPTIMIZER_HIDE_VAR(uninit_src); + DO_NOT_OPTIMIZE(uninit_src); memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src)); kmsan_check_memory((void *)dst, 4); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); @@ -467,13 +498,14 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test) kunit_info( test, "memcpy()ing aligned uninit src to unaligned dst - part 2 (UMR report)\n"); - OPTIMIZER_HIDE_VAR(uninit_src); + DO_NOT_OPTIMIZE(uninit_src); memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src)); kmsan_check_memory((void *)&dst[4], sizeof(uninit_src)); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } -static noinline void fibonacci(int *array, int size, int start) { +static noinline void fibonacci(int *array, int size, int start) +{ if (start < 2 || (start == size)) return; array[start] = array[start - 1] + array[start - 2]; @@ -482,8 +514,7 @@ static noinline void fibonacci(int *array, int size, int start) { static void test_long_origin_chain(struct kunit *test) { - EXPECTATION_UNINIT_VALUE_FN(expect, - "test_long_origin_chain"); + EXPECTATION_UNINIT_VALUE_FN(expect, "test_long_origin_chain"); /* (KMSAN_MAX_ORIGIN_DEPTH * 2) recursive calls to fibonacci(). */ volatile int accum[KMSAN_MAX_ORIGIN_DEPTH * 2 + 2]; int last = ARRAY_SIZE(accum) - 1; @@ -515,6 +546,7 @@ static struct kunit_case kmsan_test_cases[] = { KUNIT_CASE(test_uaf), KUNIT_CASE(test_percpu_propagate), KUNIT_CASE(test_printk), + KUNIT_CASE(test_init_memcpy), KUNIT_CASE(test_memcpy_aligned_to_aligned), KUNIT_CASE(test_memcpy_aligned_to_unaligned), KUNIT_CASE(test_memcpy_aligned_to_unaligned2), |