KMSAN should be overriding calls to memset/memcpy/memmove and their
__builtin_ versions in instrumented files, so there is no need to
override them. In non-instrumented versions we are now required to
leave memset() and friends intact, so we cannot replace them with
__msan_XXX() functions.
Cc: Kees Cook <[email protected]>
Suggested-by: Marco Elver <[email protected]>
Signed-off-by: Alexander Potapenko <[email protected]>
---
arch/x86/include/asm/string_64.h | 17 -----------------
1 file changed, 17 deletions(-)
diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index 888731ccf1f67..9be401d971a99 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -15,22 +15,11 @@
#endif
#define __HAVE_ARCH_MEMCPY 1
-#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)
-#undef memcpy
-#define memcpy __msan_memcpy
-#else
extern void *memcpy(void *to, const void *from, size_t len);
-#endif
extern void *__memcpy(void *to, const void *from, size_t len);
#define __HAVE_ARCH_MEMSET
-#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)
-extern void *__msan_memset(void *s, int c, size_t n);
-#undef memset
-#define memset __msan_memset
-#else
void *memset(void *s, int c, size_t n);
-#endif
void *__memset(void *s, int c, size_t n);
#define __HAVE_ARCH_MEMSET16
@@ -70,13 +59,7 @@ static inline void *memset64(uint64_t *s, uint64_t v, size_t n)
}
#define __HAVE_ARCH_MEMMOVE
-#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)
-#undef memmove
-void *__msan_memmove(void *dest, const void *src, size_t len);
-#define memmove __msan_memmove
-#else
void *memmove(void *dest, const void *src, size_t count);
-#endif
void *__memmove(void *dest, const void *src, size_t count);
int memcmp(const void *cs, const void *ct, size_t count);
--
2.39.2.722.g9855ee24e9-goog
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 asm macro that just
clobbers the memory, and add a test case for memcpy() that does not
expect an error report.
Also reflow kmsan_test.c with clang-format.
Signed-off-by: Alexander Potapenko <[email protected]>
---
mm/kmsan/kmsan_test.c | 43 +++++++++++++++++++++++++++++++++++++------
1 file changed, 37 insertions(+), 6 deletions(-)
diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c
index 088e21a48dc4b..cc98a3f4e0899 100644
--- a/mm/kmsan/kmsan_test.c
+++ b/mm/kmsan/kmsan_test.c
@@ -407,6 +407,36 @@ 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.
+ */
+#define DO_NOT_OPTIMIZE(var) asm("" ::: "memory")
+
+/*
+ * 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;
+
+ // Ensure DO_NOT_OPTIMIZE() does not cause extra checks.
+ 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 +450,7 @@ 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 +473,7 @@ 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 +497,14 @@ 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 +513,7 @@ 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 +545,7 @@ 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),
--
2.39.2.722.g9855ee24e9-goog
KMSAN must see as many memory accesses as possible to prevent false
positive reports. Fall back to versions of
memset16()/memset32()/memset64() implemented in lib/string.c instead of
those written in assembly.
Cc: Geert Uytterhoeven <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Helge Deller <[email protected]>
Suggested-by: Tetsuo Handa <[email protected]>
Signed-off-by: Alexander Potapenko <[email protected]>
---
arch/x86/include/asm/string_64.h | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index 9be401d971a99..e9c736f4686f5 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -22,6 +22,11 @@ extern void *__memcpy(void *to, const void *from, size_t len);
void *memset(void *s, int c, size_t n);
void *__memset(void *s, int c, size_t n);
+/*
+ * KMSAN needs to instrument as much code as possible. Use C versions of
+ * memsetXX() from lib/string.c under KMSAN.
+ */
+#if !defined(CONFIG_KMSAN)
#define __HAVE_ARCH_MEMSET16
static inline void *memset16(uint16_t *s, uint16_t v, size_t n)
{
@@ -57,6 +62,7 @@ static inline void *memset64(uint64_t *s, uint64_t v, size_t n)
: "memory");
return s;
}
+#endif
#define __HAVE_ARCH_MEMMOVE
void *memmove(void *dest, const void *src, size_t count);
--
2.39.2.722.g9855ee24e9-goog
Add tests ensuring that memset16()/memset32()/memset64() are
instrumented by KMSAN and correctly initialize the memory.
Signed-off-by: Alexander Potapenko <[email protected]>
---
mm/kmsan/kmsan_test.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c
index cc98a3f4e0899..e450a000441fb 100644
--- a/mm/kmsan/kmsan_test.c
+++ b/mm/kmsan/kmsan_test.c
@@ -503,6 +503,25 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test)
KUNIT_EXPECT_TRUE(test, report_matches(&expect));
}
+/* Generate test cases for memset16(), memset32(), memset64(). */
+#define DEFINE_TEST_MEMSETXX(size, var_ty) \
+ static void test_memset##size(struct kunit *test) \
+ { \
+ EXPECTATION_NO_REPORT(expect); \
+ volatile var_ty uninit; \
+ \
+ kunit_info(test, \
+ "memset" #size "() should initialize memory\n"); \
+ DO_NOT_OPTIMIZE(uninit); \
+ memset##size((var_ty *)&uninit, 0, 1); \
+ kmsan_check_memory((void *)&uninit, sizeof(uninit)); \
+ KUNIT_EXPECT_TRUE(test, report_matches(&expect)); \
+ }
+
+DEFINE_TEST_MEMSETXX(16, uint16_t)
+DEFINE_TEST_MEMSETXX(32, uint32_t)
+DEFINE_TEST_MEMSETXX(64, uint64_t)
+
static noinline void fibonacci(int *array, int size, int start)
{
if (start < 2 || (start == size))
@@ -549,6 +568,9 @@ static struct kunit_case kmsan_test_cases[] = {
KUNIT_CASE(test_memcpy_aligned_to_aligned),
KUNIT_CASE(test_memcpy_aligned_to_unaligned),
KUNIT_CASE(test_memcpy_aligned_to_unaligned2),
+ KUNIT_CASE(test_memset16),
+ KUNIT_CASE(test_memset32),
+ KUNIT_CASE(test_memset64),
KUNIT_CASE(test_long_origin_chain),
{},
};
--
2.39.2.722.g9855ee24e9-goog
On Wed, 1 Mar 2023 at 15:39, Alexander Potapenko <[email protected]> wrote:
>
> KMSAN should be overriding calls to memset/memcpy/memmove and their
You mean that the compiler will override calls?
All supported compilers that have fsanitize=kernel-memory replace
memintrinsics with __msan_mem*() calls, right?
> __builtin_ versions in instrumented files, so there is no need to
> override them. In non-instrumented versions we are now required to
> leave memset() and friends intact, so we cannot replace them with
> __msan_XXX() functions.
>
> Cc: Kees Cook <[email protected]>
> Suggested-by: Marco Elver <[email protected]>
> Signed-off-by: Alexander Potapenko <[email protected]>
Other than that,
Reviewed-by: Marco Elver <[email protected]>
> ---
> arch/x86/include/asm/string_64.h | 17 -----------------
> 1 file changed, 17 deletions(-)
>
> diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
> index 888731ccf1f67..9be401d971a99 100644
> --- a/arch/x86/include/asm/string_64.h
> +++ b/arch/x86/include/asm/string_64.h
> @@ -15,22 +15,11 @@
> #endif
>
> #define __HAVE_ARCH_MEMCPY 1
> -#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)
> -#undef memcpy
> -#define memcpy __msan_memcpy
> -#else
> extern void *memcpy(void *to, const void *from, size_t len);
> -#endif
> extern void *__memcpy(void *to, const void *from, size_t len);
>
> #define __HAVE_ARCH_MEMSET
> -#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)
> -extern void *__msan_memset(void *s, int c, size_t n);
> -#undef memset
> -#define memset __msan_memset
> -#else
> void *memset(void *s, int c, size_t n);
> -#endif
> void *__memset(void *s, int c, size_t n);
>
> #define __HAVE_ARCH_MEMSET16
> @@ -70,13 +59,7 @@ static inline void *memset64(uint64_t *s, uint64_t v, size_t n)
> }
>
> #define __HAVE_ARCH_MEMMOVE
> -#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)
> -#undef memmove
> -void *__msan_memmove(void *dest, const void *src, size_t len);
> -#define memmove __msan_memmove
> -#else
> void *memmove(void *dest, const void *src, size_t count);
> -#endif
> void *__memmove(void *dest, const void *src, size_t count);
>
> int memcmp(const void *cs, const void *ct, size_t count);
> --
> 2.39.2.722.g9855ee24e9-goog
>
On Wed, 1 Mar 2023 at 15:39, 'Alexander Potapenko' via kasan-dev
<[email protected]> wrote:
>
> 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 asm macro that just
> clobbers the memory, and add a test case for memcpy() that does not
> expect an error report.
>
> Also reflow kmsan_test.c with clang-format.
>
> Signed-off-by: Alexander Potapenko <[email protected]>
> ---
> mm/kmsan/kmsan_test.c | 43 +++++++++++++++++++++++++++++++++++++------
> 1 file changed, 37 insertions(+), 6 deletions(-)
>
> diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c
> index 088e21a48dc4b..cc98a3f4e0899 100644
> --- a/mm/kmsan/kmsan_test.c
> +++ b/mm/kmsan/kmsan_test.c
> @@ -407,6 +407,36 @@ 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.
> + */
> +#define DO_NOT_OPTIMIZE(var) asm("" ::: "memory")
That's just a normal "barrier()" - use that instead?
> +/*
> + * 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;
> +
> + // Ensure DO_NOT_OPTIMIZE() does not cause extra checks.
^^ this comment seems redundant now, given DO_NOT_OPTIMIZE() has a
comment (it's also using //-style comment).
> + 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 +450,7 @@ 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 +473,7 @@ 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 +497,14 @@ 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 +513,7 @@ 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 +545,7 @@ 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),
> --
> 2.39.2.722.g9855ee24e9-goog
>
> --
> You received this message because you are subscribed to the Google Groups "kasan-dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20230301143933.2374658-2-glider%40google.com.
On Wed, 1 Mar 2023 at 15:39, 'Alexander Potapenko' via kasan-dev
<[email protected]> wrote:
>
> KMSAN must see as many memory accesses as possible to prevent false
> positive reports. Fall back to versions of
> memset16()/memset32()/memset64() implemented in lib/string.c instead of
> those written in assembly.
>
> Cc: Geert Uytterhoeven <[email protected]>
> Cc: Daniel Vetter <[email protected]>
> Cc: Helge Deller <[email protected]>
> Suggested-by: Tetsuo Handa <[email protected]>
> Signed-off-by: Alexander Potapenko <[email protected]>
Reviewed-by: Marco Elver <[email protected]>
> ---
> arch/x86/include/asm/string_64.h | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
> index 9be401d971a99..e9c736f4686f5 100644
> --- a/arch/x86/include/asm/string_64.h
> +++ b/arch/x86/include/asm/string_64.h
> @@ -22,6 +22,11 @@ extern void *__memcpy(void *to, const void *from, size_t len);
> void *memset(void *s, int c, size_t n);
> void *__memset(void *s, int c, size_t n);
>
> +/*
> + * KMSAN needs to instrument as much code as possible. Use C versions of
> + * memsetXX() from lib/string.c under KMSAN.
> + */
> +#if !defined(CONFIG_KMSAN)
> #define __HAVE_ARCH_MEMSET16
> static inline void *memset16(uint16_t *s, uint16_t v, size_t n)
> {
> @@ -57,6 +62,7 @@ static inline void *memset64(uint64_t *s, uint64_t v, size_t n)
> : "memory");
> return s;
> }
> +#endif
>
> #define __HAVE_ARCH_MEMMOVE
> void *memmove(void *dest, const void *src, size_t count);
> --
> 2.39.2.722.g9855ee24e9-goog
>
> --
> You received this message because you are subscribed to the Google Groups "kasan-dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20230301143933.2374658-3-glider%40google.com.
On Wed, 1 Mar 2023 at 15:39, Alexander Potapenko <[email protected]> wrote:
>
> Add tests ensuring that memset16()/memset32()/memset64() are
> instrumented by KMSAN and correctly initialize the memory.
>
> Signed-off-by: Alexander Potapenko <[email protected]>
> ---
> mm/kmsan/kmsan_test.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c
> index cc98a3f4e0899..e450a000441fb 100644
> --- a/mm/kmsan/kmsan_test.c
> +++ b/mm/kmsan/kmsan_test.c
> @@ -503,6 +503,25 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test)
> KUNIT_EXPECT_TRUE(test, report_matches(&expect));
> }
>
> +/* Generate test cases for memset16(), memset32(), memset64(). */
> +#define DEFINE_TEST_MEMSETXX(size, var_ty) \
> + static void test_memset##size(struct kunit *test) \
> + { \
> + EXPECTATION_NO_REPORT(expect); \
> + volatile var_ty uninit; \
This could just be 'uint##size##_t' and you can drop 'var_ty'.
> + \
> + kunit_info(test, \
> + "memset" #size "() should initialize memory\n"); \
> + DO_NOT_OPTIMIZE(uninit); \
> + memset##size((var_ty *)&uninit, 0, 1); \
> + kmsan_check_memory((void *)&uninit, sizeof(uninit)); \
> + KUNIT_EXPECT_TRUE(test, report_matches(&expect)); \
> + }
> +
> +DEFINE_TEST_MEMSETXX(16, uint16_t)
> +DEFINE_TEST_MEMSETXX(32, uint32_t)
> +DEFINE_TEST_MEMSETXX(64, uint64_t)
> +
> static noinline void fibonacci(int *array, int size, int start)
> {
> if (start < 2 || (start == size))
> @@ -549,6 +568,9 @@ static struct kunit_case kmsan_test_cases[] = {
> KUNIT_CASE(test_memcpy_aligned_to_aligned),
> KUNIT_CASE(test_memcpy_aligned_to_unaligned),
> KUNIT_CASE(test_memcpy_aligned_to_unaligned2),
> + KUNIT_CASE(test_memset16),
> + KUNIT_CASE(test_memset32),
> + KUNIT_CASE(test_memset64),
> KUNIT_CASE(test_long_origin_chain),
> {},
> };
> --
> 2.39.2.722.g9855ee24e9-goog
>
On Thu, Mar 2, 2023 at 12:23 PM Marco Elver <[email protected]> wrote:
>
> On Wed, 1 Mar 2023 at 15:39, Alexander Potapenko <[email protected]> wrote:
> >
> > Add tests ensuring that memset16()/memset32()/memset64() are
> > instrumented by KMSAN and correctly initialize the memory.
> >
> > Signed-off-by: Alexander Potapenko <[email protected]>
> > ---
> > mm/kmsan/kmsan_test.c | 22 ++++++++++++++++++++++
> > 1 file changed, 22 insertions(+)
> >
> > diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c
> > index cc98a3f4e0899..e450a000441fb 100644
> > --- a/mm/kmsan/kmsan_test.c
> > +++ b/mm/kmsan/kmsan_test.c
> > @@ -503,6 +503,25 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test)
> > KUNIT_EXPECT_TRUE(test, report_matches(&expect));
> > }
> >
> > +/* Generate test cases for memset16(), memset32(), memset64(). */
> > +#define DEFINE_TEST_MEMSETXX(size, var_ty) \
> > + static void test_memset##size(struct kunit *test) \
> > + { \
> > + EXPECTATION_NO_REPORT(expect); \
> > + volatile var_ty uninit; \
>
> This could just be 'uint##size##_t' and you can drop 'var_ty'.
Indeed, thanks!
On Thu, Mar 2, 2023 at 12:14 PM Marco Elver <[email protected]> wrote:
>
> On Wed, 1 Mar 2023 at 15:39, Alexander Potapenko <[email protected]> wrote:
> >
> > KMSAN should be overriding calls to memset/memcpy/memmove and their
>
> You mean that the compiler will override calls?
> All supported compilers that have fsanitize=kernel-memory replace
> memintrinsics with __msan_mem*() calls, right?
Right. Changed to:
KMSAN already replaces calls to to memset/memcpy/memmove and their
__builtin_ versions with __msan_memset/__msan_memcpy/__msan_memmove in
instrumented files, so there is no need to override them.
>
> > __builtin_ versions in instrumented files, so there is no need to
> > override them. In non-instrumented versions we are now required to
> > leave memset() and friends intact, so we cannot replace them with
> > __msan_XXX() functions.
> >
> > Cc: Kees Cook <[email protected]>
> > Suggested-by: Marco Elver <[email protected]>
> > Signed-off-by: Alexander Potapenko <[email protected]>
>
> Other than that,
>
> Reviewed-by: Marco Elver <[email protected]>
Thanks!
> > +#define DO_NOT_OPTIMIZE(var) asm("" ::: "memory")
>
> That's just a normal "barrier()" - use that instead?
Ok, will do (I still think I'd better hide it behind a macro so that
we can change the implementation of DO_NOT_OPTIMIZE in the future if
the compiler starts outsmarting us again.
> > +/*
> > + * 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;
> > +
> > + // Ensure DO_NOT_OPTIMIZE() does not cause extra checks.
>
> ^^ this comment seems redundant now, given DO_NOT_OPTIMIZE() has a
> comment (it's also using //-style comment).
Moved it to the test description:
/*
* 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.
*/
I think it's still relevant here.
On Thu, 2 Mar 2023 at 15:28, Alexander Potapenko <[email protected]> wrote:
>
> On Thu, Mar 2, 2023 at 12:14 PM Marco Elver <[email protected]> wrote:
> >
> > On Wed, 1 Mar 2023 at 15:39, Alexander Potapenko <[email protected]> wrote:
> > >
> > > KMSAN should be overriding calls to memset/memcpy/memmove and their
> >
> > You mean that the compiler will override calls?
> > All supported compilers that have fsanitize=kernel-memory replace
> > memintrinsics with __msan_mem*() calls, right?
>
> Right. Changed to:
>
> KMSAN already replaces calls to to memset/memcpy/memmove and their
> __builtin_ versions with __msan_memset/__msan_memcpy/__msan_memmove in
> instrumented files, so there is no need to override them.
But it's not KMSAN - KMSAN is the combined end result of runtime and
compiler - in this case we need to be specific and point out it's the
compiler that's doing it. There is no code in the Linux kernel that
does this replacement.
>
> >
> > > __builtin_ versions in instrumented files, so there is no need to
> > > override them. In non-instrumented versions we are now required to
> > > leave memset() and friends intact, so we cannot replace them with
> > > __msan_XXX() functions.
> > >
> > > Cc: Kees Cook <[email protected]>
> > > Suggested-by: Marco Elver <[email protected]>
> > > Signed-off-by: Alexander Potapenko <[email protected]>
> >
> > Other than that,
> >
> > Reviewed-by: Marco Elver <[email protected]>
> Thanks!
On Thu, Mar 2, 2023 at 4:13 PM Marco Elver <[email protected]> wrote:
>
> On Thu, 2 Mar 2023 at 15:28, Alexander Potapenko <[email protected]> wrote:
> >
> > On Thu, Mar 2, 2023 at 12:14 PM Marco Elver <[email protected]> wrote:
> > >
> > > On Wed, 1 Mar 2023 at 15:39, Alexander Potapenko <[email protected]> wrote:
> > > >
> > > > KMSAN should be overriding calls to memset/memcpy/memmove and their
> > >
> > > You mean that the compiler will override calls?
> > > All supported compilers that have fsanitize=kernel-memory replace
> > > memintrinsics with __msan_mem*() calls, right?
> >
> > Right. Changed to:
> >
> > KMSAN already replaces calls to to memset/memcpy/memmove and their
> > __builtin_ versions with __msan_memset/__msan_memcpy/__msan_memmove in
> > instrumented files, so there is no need to override them.
>
> But it's not KMSAN - KMSAN is the combined end result of runtime and
> compiler - in this case we need to be specific and point out it's the
> compiler that's doing it. There is no code in the Linux kernel that
> does this replacement.
Agreed. I'll replace with "clang -fsanitize=kernel-memory"