diff mbox series

[v2] kunit: kasan_test: disable fortify string checker on kmalloc_oob_memset

Message ID 20231214164423.6202-1-npache@redhat.com
State New
Headers
Series [v2] kunit: kasan_test: disable fortify string checker on kmalloc_oob_memset |

Commit Message

Nico Pache Dec. 14, 2023, 4:44 p.m. UTC 
  similar to commit 09c6304e38e4 ("kasan: test: fix compatibility with
FORTIFY_SOURCE") the kernel is panicing in kmalloc_oob_memset_*.

This is due to the `ptr` not being hidden from the optimizer which would
disable the runtime fortify string checker.

kernel BUG at lib/string_helpers.c:1048!
Call Trace:
[<00000000272502e2>] fortify_panic+0x2a/0x30
([<00000000272502de>] fortify_panic+0x26/0x30)
[<001bffff817045c4>] kmalloc_oob_memset_2+0x22c/0x230 [kasan_test]

Hide the `ptr` variable from the optimizer to fix the kernel panic.
Also define a memset_size variable and hide that as well. This cleans up
the code and follows the same convention as other tests.

Signed-off-by: Nico Pache <npache@redhat.com>
---
 mm/kasan/kasan_test.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

Comments

Andrey Konovalov Dec. 14, 2023, 9:25 p.m. UTC | #1 
On Thu, Dec 14, 2023 at 5:44 PM Nico Pache <npache@redhat.com> wrote:
>
> similar to commit 09c6304e38e4 ("kasan: test: fix compatibility with
> FORTIFY_SOURCE") the kernel is panicing in kmalloc_oob_memset_*.
>
> This is due to the `ptr` not being hidden from the optimizer which would
> disable the runtime fortify string checker.
>
> kernel BUG at lib/string_helpers.c:1048!
> Call Trace:
> [<00000000272502e2>] fortify_panic+0x2a/0x30
> ([<00000000272502de>] fortify_panic+0x26/0x30)
> [<001bffff817045c4>] kmalloc_oob_memset_2+0x22c/0x230 [kasan_test]
>
> Hide the `ptr` variable from the optimizer to fix the kernel panic.
> Also define a memset_size variable and hide that as well. This cleans up
> the code and follows the same convention as other tests.
>
> Signed-off-by: Nico Pache <npache@redhat.com>
> ---
>  mm/kasan/kasan_test.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c
> index 8281eb42464b..34515a106ca5 100644
> --- a/mm/kasan/kasan_test.c
> +++ b/mm/kasan/kasan_test.c
> @@ -493,14 +493,17 @@ static void kmalloc_oob_memset_2(struct kunit *test)
>  {
>         char *ptr;
>         size_t size = 128 - KASAN_GRANULE_SIZE;
> +       size_t memset_size = 2;
>
>         KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
>
>         ptr = kmalloc(size, GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>
> +       OPTIMIZER_HIDE_VAR(ptr);
>         OPTIMIZER_HIDE_VAR(size);
> -       KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 1, 0, 2));
> +       OPTIMIZER_HIDE_VAR(memset_size);
> +       KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 1, 0, memset_size));
>         kfree(ptr);
>  }
>
> @@ -508,14 +511,17 @@ static void kmalloc_oob_memset_4(struct kunit *test)
>  {
>         char *ptr;
>         size_t size = 128 - KASAN_GRANULE_SIZE;
> +       size_t memset_size = 4;
>
>         KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
>
>         ptr = kmalloc(size, GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>
> +       OPTIMIZER_HIDE_VAR(ptr);
>         OPTIMIZER_HIDE_VAR(size);
> -       KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 3, 0, 4));
> +       OPTIMIZER_HIDE_VAR(memset_size);
> +       KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 3, 0, memset_size));
>         kfree(ptr);
>  }
>
> @@ -523,14 +529,17 @@ static void kmalloc_oob_memset_8(struct kunit *test)
>  {
>         char *ptr;
>         size_t size = 128 - KASAN_GRANULE_SIZE;
> +       size_t memset_size = 8;
>
>         KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
>
>         ptr = kmalloc(size, GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>
> +       OPTIMIZER_HIDE_VAR(ptr);
>         OPTIMIZER_HIDE_VAR(size);
> -       KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 7, 0, 8));
> +       OPTIMIZER_HIDE_VAR(memset_size);
> +       KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 7, 0, memset_size));
>         kfree(ptr);
>  }
>
> @@ -538,14 +547,17 @@ static void kmalloc_oob_memset_16(struct kunit *test)
>  {
>         char *ptr;
>         size_t size = 128 - KASAN_GRANULE_SIZE;
> +       size_t memset_size = 16;
>
>         KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
>
>         ptr = kmalloc(size, GFP_KERNEL);
>         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
>
> +       OPTIMIZER_HIDE_VAR(ptr);
>         OPTIMIZER_HIDE_VAR(size);
> -       KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 15, 0, 16));
> +       OPTIMIZER_HIDE_VAR(memset_size);
> +       KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 15, 0, memset_size));
>         kfree(ptr);
>  }
>
> --
> 2.43.0
>

Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>

Thanks!
diff mbox series

Patch

diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c
index 8281eb42464b..34515a106ca5 100644
--- a/mm/kasan/kasan_test.c
+++ b/mm/kasan/kasan_test.c
@@ -493,14 +493,17 @@  static void kmalloc_oob_memset_2(struct kunit *test)
 {
 	char *ptr;
 	size_t size = 128 - KASAN_GRANULE_SIZE;
+	size_t memset_size = 2;
 
 	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	OPTIMIZER_HIDE_VAR(size);
-	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 1, 0, 2));
+	OPTIMIZER_HIDE_VAR(memset_size);
+	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 1, 0, memset_size));
 	kfree(ptr);
 }
 
@@ -508,14 +511,17 @@  static void kmalloc_oob_memset_4(struct kunit *test)
 {
 	char *ptr;
 	size_t size = 128 - KASAN_GRANULE_SIZE;
+	size_t memset_size = 4;
 
 	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	OPTIMIZER_HIDE_VAR(size);
-	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 3, 0, 4));
+	OPTIMIZER_HIDE_VAR(memset_size);
+	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 3, 0, memset_size));
 	kfree(ptr);
 }
 
@@ -523,14 +529,17 @@  static void kmalloc_oob_memset_8(struct kunit *test)
 {
 	char *ptr;
 	size_t size = 128 - KASAN_GRANULE_SIZE;
+	size_t memset_size = 8;
 
 	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	OPTIMIZER_HIDE_VAR(size);
-	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 7, 0, 8));
+	OPTIMIZER_HIDE_VAR(memset_size);
+	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 7, 0, memset_size));
 	kfree(ptr);
 }
 
@@ -538,14 +547,17 @@  static void kmalloc_oob_memset_16(struct kunit *test)
 {
 	char *ptr;
 	size_t size = 128 - KASAN_GRANULE_SIZE;
+	size_t memset_size = 16;
 
 	KASAN_TEST_NEEDS_CHECKED_MEMINTRINSICS(test);
 
 	ptr = kmalloc(size, GFP_KERNEL);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
+	OPTIMIZER_HIDE_VAR(ptr);
 	OPTIMIZER_HIDE_VAR(size);
-	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 15, 0, 16));
+	OPTIMIZER_HIDE_VAR(memset_size);
+	KUNIT_EXPECT_KASAN_FAIL(test, memset(ptr + size - 15, 0, memset_size));
 	kfree(ptr);
 }