From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Subject: kasan: clean up comments in tests Clarify and update comments in KASAN tests. Link: https://linux-review.googlesource.com/id/I6c816c51fa1e0eb7aa3dead6bda1f339d2af46c8 Link: https://lkml.kernel.org/r/ba6db104d53ae0e3796f80ef395f6873c1c1282f.1610733117.git.andreyknvl@xxxxxxxxxx Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Branislav Rankov <Branislav.Rankov@xxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx> Cc: Kevin Brodsky <kevin.brodsky@xxxxxxx> Cc: Peter Collingbourne <pcc@xxxxxxxxxx> Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/test_kasan.c | 59 +++++++++++++++++++++++--------------- lib/test_kasan_module.c | 5 +-- 2 files changed, 39 insertions(+), 25 deletions(-) --- a/lib/test_kasan.c~kasan-clean-up-comments-in-tests +++ a/lib/test_kasan.c @@ -28,10 +28,9 @@ #define OOB_TAG_OFF (IS_ENABLED(CONFIG_KASAN_GENERIC) ? 0 : KASAN_GRANULE_SIZE) /* - * We assign some test results to these globals to make sure the tests - * are not eliminated as dead code. + * Some tests use these global variables to store return values from function + * calls that could otherwise be eliminated by the compiler as dead code. */ - void *kasan_ptr_result; int kasan_int_result; @@ -39,14 +38,13 @@ static struct kunit_resource resource; static struct kunit_kasan_expectation fail_data; static bool multishot; +/* + * Temporarily enable multi-shot mode. Otherwise, KASAN would only report the + * first detected bug and panic the kernel if panic_on_warn is enabled. + */ static int kasan_test_init(struct kunit *test) { - /* - * Temporarily enable multi-shot mode and set panic_on_warn=0. - * Otherwise, we'd only get a report for the first case. - */ multishot = kasan_save_enable_multi_shot(); - return 0; } @@ -56,12 +54,12 @@ static void kasan_test_exit(struct kunit } /** - * KUNIT_EXPECT_KASAN_FAIL() - Causes a test failure when the expression does - * not cause a KASAN error. This uses a KUnit resource named "kasan_data." Do - * Do not use this name for a KUnit resource outside here. - * + * KUNIT_EXPECT_KASAN_FAIL() - check that the executed expression produces a + * KASAN report; causes a test failure otherwise. This relies on a KUnit + * resource named "kasan_data". Do not use this name for KUnit resources + * outside of KASAN tests. */ -#define KUNIT_EXPECT_KASAN_FAIL(test, condition) do { \ +#define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \ fail_data.report_expected = true; \ fail_data.report_found = false; \ kunit_add_named_resource(test, \ @@ -69,7 +67,7 @@ static void kasan_test_exit(struct kunit NULL, \ &resource, \ "kasan_data", &fail_data); \ - condition; \ + expression; \ KUNIT_EXPECT_EQ(test, \ fail_data.report_expected, \ fail_data.report_found); \ @@ -121,7 +119,8 @@ static void kmalloc_pagealloc_oob_right( return; } - /* Allocate a chunk that does not fit into a SLUB cache to trigger + /* + * Allocate a chunk that does not fit into a SLUB cache to trigger * the page allocator fallback. */ ptr = kmalloc(size, GFP_KERNEL); @@ -168,7 +167,9 @@ static void kmalloc_large_oob_right(stru { char *ptr; size_t size = KMALLOC_MAX_CACHE_SIZE - 256; - /* Allocate a chunk that is large enough, but still fits into a slab + + /* + * Allocate a chunk that is large enough, but still fits into a slab * and does not trigger the page allocator fallback in SLUB. */ ptr = kmalloc(size, GFP_KERNEL); @@ -469,10 +470,13 @@ static void ksize_unpoisons_memory(struc ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); real_size = ksize(ptr); - /* This access doesn't trigger an error. */ + + /* This access shouldn't trigger a KASAN report. */ ptr[size] = 'x'; - /* This one does. */ + + /* This one must. */ KUNIT_EXPECT_KASAN_FAIL(test, ptr[real_size] = 'y'); + kfree(ptr); } @@ -568,7 +572,7 @@ static void kmem_cache_invalid_free(stru return; } - /* Trigger invalid free, the object doesn't get freed */ + /* Trigger invalid free, the object doesn't get freed. */ KUNIT_EXPECT_KASAN_FAIL(test, kmem_cache_free(cache, p + 1)); /* @@ -585,7 +589,10 @@ static void kasan_memchr(struct kunit *t char *ptr; size_t size = 24; - /* See https://bugzilla.kernel.org/show_bug.cgi?id=206337 */ + /* + * str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT. + * See https://bugzilla.kernel.org/show_bug.cgi?id=206337 for details. + */ if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { kunit_info(test, "str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT"); @@ -610,7 +617,10 @@ static void kasan_memcmp(struct kunit *t size_t size = 24; int arr[9]; - /* See https://bugzilla.kernel.org/show_bug.cgi?id=206337 */ + /* + * str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT. + * See https://bugzilla.kernel.org/show_bug.cgi?id=206337 for details. + */ if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { kunit_info(test, "str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT"); @@ -634,7 +644,10 @@ static void kasan_strings(struct kunit * char *ptr; size_t size = 24; - /* See https://bugzilla.kernel.org/show_bug.cgi?id=206337 */ + /* + * str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT. + * See https://bugzilla.kernel.org/show_bug.cgi?id=206337 for details. + */ if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { kunit_info(test, "str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT"); @@ -706,7 +719,7 @@ static void kasan_bitops_generic(struct } /* - * Allocate 1 more byte, which causes kzalloc to round up to 16-bytes; + * Allocate 1 more byte, which causes kzalloc to round up to 16 bytes; * this way we do not actually corrupt other memory. */ bits = kzalloc(sizeof(*bits) + 1, GFP_KERNEL); --- a/lib/test_kasan_module.c~kasan-clean-up-comments-in-tests +++ a/lib/test_kasan_module.c @@ -123,8 +123,9 @@ static noinline void __init kasan_workqu static int __init test_kasan_module_init(void) { /* - * Temporarily enable multi-shot mode. Otherwise, we'd only get a - * report for the first case. + * Temporarily enable multi-shot mode. Otherwise, KASAN would only + * report the first detected bug and panic the kernel if panic_on_warn + * is enabled. */ bool multishot = kasan_save_enable_multi_shot(); _
