summaryrefslogtreecommitdiffstats
path: root/mm/kmsan/kmsan_test.c
diff options
context:
space:
mode:
Diffstat (limited to 'mm/kmsan/kmsan_test.c')
-rw-r--r--mm/kmsan/kmsan_test.c109
1 files changed, 71 insertions, 38 deletions
diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c
index 312989aa28..07d3a3a5a9 100644
--- a/mm/kmsan/kmsan_test.c
+++ b/mm/kmsan/kmsan_test.c
@@ -67,6 +67,17 @@ static bool report_available(void)
return READ_ONCE(observed.available);
}
+/* Reset observed.available, so that the test can trigger another report. */
+static void report_reset(void)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&observed.lock, flags);
+ WRITE_ONCE(observed.available, false);
+ observed.ignore = false;
+ spin_unlock_irqrestore(&observed.lock, flags);
+}
+
/* Information we expect in a report. */
struct expect_report {
const char *error_type; /* Error type. */
@@ -407,33 +418,25 @@ static void test_printk(struct kunit *test)
KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}
-/*
- * 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()
+/* Prevent the compiler from inlining a memcpy() call. */
+static noinline void *memcpy_noinline(volatile void *dst,
+ const volatile void *src, size_t size)
+{
+ return memcpy((void *)dst, (const void *)src, size);
+}
-/*
- * 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.
- */
+/* Test case: ensure that memcpy() correctly copies initialized values. */
static void test_init_memcpy(struct kunit *test)
{
EXPECTATION_NO_REPORT(expect);
- volatile int src;
- volatile int dst = 0;
+ volatile long long src;
+ volatile long long 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));
+ memcpy_noinline((void *)&dst, (void *)&src, sizeof(src));
kmsan_check_memory((void *)&dst, sizeof(dst));
KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}
@@ -451,8 +454,7 @@ static void test_memcpy_aligned_to_aligned(struct kunit *test)
kunit_info(
test,
"memcpy()ing aligned uninit src to aligned dst (UMR report)\n");
- DO_NOT_OPTIMIZE(uninit_src);
- memcpy((void *)&dst, (void *)&uninit_src, sizeof(uninit_src));
+ memcpy_noinline((void *)&dst, (void *)&uninit_src, sizeof(uninit_src));
kmsan_check_memory((void *)&dst, sizeof(dst));
KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}
@@ -463,7 +465,7 @@ static void test_memcpy_aligned_to_aligned(struct kunit *test)
*
* Copying aligned 4-byte value to an unaligned one leads to touching two
* aligned 4-byte values. This test case checks that KMSAN correctly reports an
- * error on the first of the two values.
+ * error on the mentioned two values.
*/
static void test_memcpy_aligned_to_unaligned(struct kunit *test)
{
@@ -474,33 +476,65 @@ static void test_memcpy_aligned_to_unaligned(struct kunit *test)
kunit_info(
test,
"memcpy()ing aligned uninit src to unaligned dst (UMR report)\n");
- DO_NOT_OPTIMIZE(uninit_src);
- memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src));
+ kmsan_check_memory((void *)&uninit_src, sizeof(uninit_src));
+ memcpy_noinline((void *)&dst[1], (void *)&uninit_src,
+ sizeof(uninit_src));
kmsan_check_memory((void *)dst, 4);
KUNIT_EXPECT_TRUE(test, report_matches(&expect));
+ report_reset();
+ kmsan_check_memory((void *)&dst[4], sizeof(uninit_src));
+ KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}
/*
- * Test case: ensure that memcpy() correctly copies uninitialized values between
- * aligned `src` and unaligned `dst`.
+ * Test case: ensure that origin slots do not accidentally get overwritten with
+ * zeroes during memcpy().
*
- * Copying aligned 4-byte value to an unaligned one leads to touching two
- * aligned 4-byte values. This test case checks that KMSAN correctly reports an
- * error on the second of the two values.
+ * 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_aligned_to_unaligned2(struct kunit *test)
+static void test_memcpy_initialized_gap(struct kunit *test)
{
- EXPECTATION_UNINIT_VALUE_FN(expect,
- "test_memcpy_aligned_to_unaligned2");
- volatile int uninit_src;
+ EXPECTATION_UNINIT_VALUE_FN(expect, "test_memcpy_initialized_gap");
+ volatile char uninit_src[12];
volatile char dst[8] = { 0 };
kunit_info(
test,
- "memcpy()ing aligned uninit src to unaligned dst - part 2 (UMR report)\n");
- DO_NOT_OPTIMIZE(uninit_src);
- memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src));
- kmsan_check_memory((void *)&dst[4], sizeof(uninit_src));
+ "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));
}
@@ -513,7 +547,6 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test)
\
kunit_info(test, \
"memset" #size "() should initialize memory\n"); \
- DO_NOT_OPTIMIZE(uninit); \
memset##size((uint##size##_t *)&uninit, 0, 1); \
kmsan_check_memory((void *)&uninit, sizeof(uninit)); \
KUNIT_EXPECT_TRUE(test, report_matches(&expect)); \
@@ -598,7 +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_aligned_to_unaligned2),
+ KUNIT_CASE(test_memcpy_initialized_gap),
KUNIT_CASE(test_memset16),
KUNIT_CASE(test_memset32),
KUNIT_CASE(test_memset64),