| Message ID | 20230911145702.2663753-4-glider@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/4] kmsan: simplify kmsan_internal_memmove_metadata() | expand |
On Mon, 11 Sept 2023 at 16:57, Alexander Potapenko <glider@google.com> wrote: > > Add a regression test for the special case where memcpy() previously > failed to correctly set the origins: if upon memcpy() four aligned > initialized bytes with a zero origin value ended up split between two > aligned four-byte chunks, one of those chunks could've received the zero > origin value even despite it contained uninitialized bytes from other > writes. > > Signed-off-by: Alexander Potapenko <glider@google.com> > Suggested-by: Marco Elver <elver@google.com> Acked-by: Marco Elver <elver@google.com> > --- > mm/kmsan/kmsan_test.c | 53 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 53 insertions(+) > > diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c > index 6eb1e1a4d08f9..07d3a3a5a9c52 100644 > --- a/mm/kmsan/kmsan_test.c > +++ b/mm/kmsan/kmsan_test.c > @@ -486,6 +486,58 @@ static void test_memcpy_aligned_to_unaligned(struct kunit *test) > KUNIT_EXPECT_TRUE(test, report_matches(&expect)); > } > > +/* > + * Test case: ensure that origin slots do not accidentally get overwritten with > + * zeroes during memcpy(). > + * > + * Previously, when copying memory from an aligned buffer to an unaligned one, > + * if there were zero origins corresponding to zero shadow values in the source > + * buffer, they could have ended up being copied to nonzero shadow values in the > + * destination buffer: > + * > + * memcpy(0xffff888080a00000, 0xffff888080900002, 8) > + * > + * src (0xffff888080900002): ..xx .... xx.. > + * src origins: o111 0000 o222 > + * dst (0xffff888080a00000): xx.. ..xx > + * dst origins: o111 0000 > + * (or 0000 o222) > + * > + * (here . stands for an initialized byte, and x for an uninitialized one. > + * > + * Ensure that this does not happen anymore, and for both destination bytes > + * the origin is nonzero (i.e. KMSAN reports an error). > + */ > +static void test_memcpy_initialized_gap(struct kunit *test) > +{ > + EXPECTATION_UNINIT_VALUE_FN(expect, "test_memcpy_initialized_gap"); > + volatile char uninit_src[12]; > + volatile char dst[8] = { 0 }; > + > + kunit_info( > + test, > + "unaligned 4-byte initialized value gets a nonzero origin after memcpy() - (2 UMR reports)\n"); > + > + uninit_src[0] = 42; > + uninit_src[1] = 42; > + uninit_src[4] = 42; > + uninit_src[5] = 42; > + uninit_src[6] = 42; > + uninit_src[7] = 42; > + uninit_src[10] = 42; > + uninit_src[11] = 42; > + memcpy_noinline((void *)&dst[0], (void *)&uninit_src[2], 8); > + > + kmsan_check_memory((void *)&dst[0], 4); > + KUNIT_EXPECT_TRUE(test, report_matches(&expect)); > + report_reset(); > + kmsan_check_memory((void *)&dst[2], 4); > + KUNIT_EXPECT_FALSE(test, report_matches(&expect)); > + report_reset(); > + kmsan_check_memory((void *)&dst[4], 4); > + KUNIT_EXPECT_TRUE(test, report_matches(&expect)); > +} > + > /* Generate test cases for memset16(), memset32(), memset64(). */ > #define DEFINE_TEST_MEMSETXX(size) \ > static void test_memset##size(struct kunit *test) \ > @@ -579,6 +631,7 @@ static struct kunit_case kmsan_test_cases[] = { > KUNIT_CASE(test_init_memcpy), > KUNIT_CASE(test_memcpy_aligned_to_aligned), > KUNIT_CASE(test_memcpy_aligned_to_unaligned), > + KUNIT_CASE(test_memcpy_initialized_gap), > KUNIT_CASE(test_memset16), > KUNIT_CASE(test_memset32), > KUNIT_CASE(test_memset64), > -- > 2.42.0.283.g2d96d420d3-goog >
diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c index 6eb1e1a4d08f9..07d3a3a5a9c52 100644 --- a/mm/kmsan/kmsan_test.c +++ b/mm/kmsan/kmsan_test.c @@ -486,6 +486,58 @@ static void test_memcpy_aligned_to_unaligned(struct kunit *test) KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } +/* + * Test case: ensure that origin slots do not accidentally get overwritten with + * zeroes during memcpy(). + * + * Previously, when copying memory from an aligned buffer to an unaligned one, + * if there were zero origins corresponding to zero shadow values in the source + * buffer, they could have ended up being copied to nonzero shadow values in the + * destination buffer: + * + * memcpy(0xffff888080a00000, 0xffff888080900002, 8) + * + * src (0xffff888080900002): ..xx .... xx.. + * src origins: o111 0000 o222 + * dst (0xffff888080a00000): xx.. ..xx + * dst origins: o111 0000 + * (or 0000 o222) + * + * (here . stands for an initialized byte, and x for an uninitialized one. + * + * Ensure that this does not happen anymore, and for both destination bytes + * the origin is nonzero (i.e. KMSAN reports an error). + */ +static void test_memcpy_initialized_gap(struct kunit *test) +{ + EXPECTATION_UNINIT_VALUE_FN(expect, "test_memcpy_initialized_gap"); + volatile char uninit_src[12]; + volatile char dst[8] = { 0 }; + + kunit_info( + test, + "unaligned 4-byte initialized value gets a nonzero origin after memcpy() - (2 UMR reports)\n"); + + uninit_src[0] = 42; + uninit_src[1] = 42; + uninit_src[4] = 42; + uninit_src[5] = 42; + uninit_src[6] = 42; + uninit_src[7] = 42; + uninit_src[10] = 42; + uninit_src[11] = 42; + memcpy_noinline((void *)&dst[0], (void *)&uninit_src[2], 8); + + kmsan_check_memory((void *)&dst[0], 4); + KUNIT_EXPECT_TRUE(test, report_matches(&expect)); + report_reset(); + kmsan_check_memory((void *)&dst[2], 4); + KUNIT_EXPECT_FALSE(test, report_matches(&expect)); + report_reset(); + kmsan_check_memory((void *)&dst[4], 4); + KUNIT_EXPECT_TRUE(test, report_matches(&expect)); +} + /* Generate test cases for memset16(), memset32(), memset64(). */ #define DEFINE_TEST_MEMSETXX(size) \ static void test_memset##size(struct kunit *test) \ @@ -579,6 +631,7 @@ static struct kunit_case kmsan_test_cases[] = { KUNIT_CASE(test_init_memcpy), KUNIT_CASE(test_memcpy_aligned_to_aligned), KUNIT_CASE(test_memcpy_aligned_to_unaligned), + KUNIT_CASE(test_memcpy_initialized_gap), KUNIT_CASE(test_memset16), KUNIT_CASE(test_memset32), KUNIT_CASE(test_memset64),
Add a regression test for the special case where memcpy() previously failed to correctly set the origins: if upon memcpy() four aligned initialized bytes with a zero origin value ended up split between two aligned four-byte chunks, one of those chunks could've received the zero origin value even despite it contained uninitialized bytes from other writes. Signed-off-by: Alexander Potapenko <glider@google.com> Suggested-by: Marco Elver <elver@google.com> --- mm/kmsan/kmsan_test.c | 53 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+)