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    SubjectRe: [PATCH 03/11] kasan: clean up comments in tests
    On Tue, Jan 05, 2021 at 07:27PM +0100, Andrey Konovalov wrote:
    > Clarify and update comments and info messages in KASAN tests.
    >
    > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
    > Link: https://linux-review.googlesource.com/id/I6c816c51fa1e0eb7aa3dead6bda1f339d2af46c8

    Reviewed-by: Marco Elver <elver@google.com>

    > ---
    > lib/test_kasan.c | 94 +++++++++++++++++++++++------------------
    > lib/test_kasan_module.c | 5 ++-
    > 2 files changed, 55 insertions(+), 44 deletions(-)
    >
    > diff --git a/lib/test_kasan.c b/lib/test_kasan.c
    > index 2947274cc2d3..46e578c8e842 100644
    > --- a/lib/test_kasan.c
    > +++ b/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 *test)
    > }
    >
    > /**
    > - * 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 *test)
    > NULL, \
    > &resource, \
    > "kasan_data", &fail_data); \
    > - condition; \
    > + expression; \
    > KUNIT_EXPECT_EQ(test, \
    > fail_data.report_expected, \
    > fail_data.report_found); \
    > @@ -117,11 +115,12 @@ static void kmalloc_pagealloc_oob_right(struct kunit *test)
    > size_t size = KMALLOC_MAX_CACHE_SIZE + 10;
    >
    > if (!IS_ENABLED(CONFIG_SLUB)) {
    > - kunit_info(test, "CONFIG_SLUB is not enabled.");
    > + kunit_info(test, "skipping, CONFIG_SLUB required");
    > 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);
    > @@ -137,7 +136,7 @@ static void kmalloc_pagealloc_uaf(struct kunit *test)
    > size_t size = KMALLOC_MAX_CACHE_SIZE + 10;
    >
    > if (!IS_ENABLED(CONFIG_SLUB)) {
    > - kunit_info(test, "CONFIG_SLUB is not enabled.");
    > + kunit_info(test, "skipping, CONFIG_SLUB required");
    > return;
    > }
    >
    > @@ -154,7 +153,7 @@ static void kmalloc_pagealloc_invalid_free(struct kunit *test)
    > size_t size = KMALLOC_MAX_CACHE_SIZE + 10;
    >
    > if (!IS_ENABLED(CONFIG_SLUB)) {
    > - kunit_info(test, "CONFIG_SLUB is not enabled.");
    > + kunit_info(test, "skipping, CONFIG_SLUB required");
    > return;
    > }
    >
    > @@ -168,7 +167,9 @@ static void kmalloc_large_oob_right(struct kunit *test)
    > {
    > 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);
    > @@ -218,7 +219,7 @@ static void kmalloc_oob_16(struct kunit *test)
    >
    > /* This test is specifically crafted for the generic mode. */
    > if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) {
    > - kunit_info(test, "CONFIG_KASAN_GENERIC required\n");
    > + kunit_info(test, "skipping, CONFIG_KASAN_GENERIC required");
    > return;
    > }
    >
    > @@ -454,7 +455,7 @@ static void kasan_global_oob(struct kunit *test)
    >
    > /* Only generic mode instruments globals. */
    > if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) {
    > - kunit_info(test, "CONFIG_KASAN_GENERIC required");
    > + kunit_info(test, "skipping, CONFIG_KASAN_GENERIC required");
    > return;
    > }
    >
    > @@ -469,10 +470,13 @@ static void ksize_unpoisons_memory(struct kunit *test)
    > 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);
    > }
    >
    > @@ -483,7 +487,7 @@ static void kasan_stack_oob(struct kunit *test)
    > char *p = &stack_array[ARRAY_SIZE(stack_array) + i];
    >
    > if (!IS_ENABLED(CONFIG_KASAN_STACK)) {
    > - kunit_info(test, "CONFIG_KASAN_STACK is not enabled");
    > + kunit_info(test, "skipping, CONFIG_KASAN_STACK required");
    > return;
    > }
    >
    > @@ -498,12 +502,12 @@ static void kasan_alloca_oob_left(struct kunit *test)
    >
    > /* Only generic mode instruments dynamic allocas. */
    > if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) {
    > - kunit_info(test, "CONFIG_KASAN_GENERIC required");
    > + kunit_info(test, "skipping, CONFIG_KASAN_GENERIC required");
    > return;
    > }
    >
    > if (!IS_ENABLED(CONFIG_KASAN_STACK)) {
    > - kunit_info(test, "CONFIG_KASAN_STACK is not enabled");
    > + kunit_info(test, "skipping, CONFIG_KASAN_STACK required");
    > return;
    > }
    >
    > @@ -518,12 +522,12 @@ static void kasan_alloca_oob_right(struct kunit *test)
    >
    > /* Only generic mode instruments dynamic allocas. */
    > if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) {
    > - kunit_info(test, "CONFIG_KASAN_GENERIC required");
    > + kunit_info(test, "skipping, CONFIG_KASAN_GENERIC required");
    > return;
    > }
    >
    > if (!IS_ENABLED(CONFIG_KASAN_STACK)) {
    > - kunit_info(test, "CONFIG_KASAN_STACK is not enabled");
    > + kunit_info(test, "skipping, CONFIG_KASAN_STACK required");
    > return;
    > }
    >
    > @@ -568,7 +572,7 @@ static void kmem_cache_invalid_free(struct kunit *test)
    > 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));
    >
    > /*
    > @@ -585,10 +589,12 @@ static void kasan_memchr(struct kunit *test)
    > 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");
    > + kunit_info(test, "skipping, CONFIG_AMD_MEM_ENCRYPT enabled");
    > return;
    > }
    >
    > @@ -610,10 +616,12 @@ static void kasan_memcmp(struct kunit *test)
    > 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");
    > + kunit_info(test, "skipping, CONFIG_AMD_MEM_ENCRYPT enabled");
    > return;
    > }
    >
    > @@ -634,10 +642,12 @@ static void kasan_strings(struct kunit *test)
    > 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");
    > + kunit_info(test, "skipping, CONFIG_AMD_MEM_ENCRYPT enabled");
    > return;
    > }
    >
    > @@ -701,12 +711,12 @@ static void kasan_bitops_generic(struct kunit *test)
    >
    > /* This test is specifically crafted for the generic mode. */
    > if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) {
    > - kunit_info(test, "CONFIG_KASAN_GENERIC required\n");
    > + kunit_info(test, "skipping, CONFIG_KASAN_GENERIC required");
    > return;
    > }
    >
    > /*
    > - * 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);
    > @@ -733,7 +743,7 @@ static void kasan_bitops_tags(struct kunit *test)
    >
    > /* This test is specifically crafted for the tag-based mode. */
    > if (IS_ENABLED(CONFIG_KASAN_GENERIC)) {
    > - kunit_info(test, "CONFIG_KASAN_SW_TAGS required\n");
    > + kunit_info(test, "skipping, CONFIG_KASAN_SW_TAGS required");
    > return;
    > }
    >
    > @@ -765,7 +775,7 @@ static void vmalloc_oob(struct kunit *test)
    > void *area;
    >
    > if (!IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
    > - kunit_info(test, "CONFIG_KASAN_VMALLOC is not enabled.");
    > + kunit_info(test, "skipping, CONFIG_KASAN_VMALLOC required");
    > return;
    > }
    >
    > diff --git a/lib/test_kasan_module.c b/lib/test_kasan_module.c
    > index 3b4cc77992d2..eee017ff8980 100644
    > --- a/lib/test_kasan_module.c
    > +++ b/lib/test_kasan_module.c
    > @@ -123,8 +123,9 @@ static noinline void __init kasan_workqueue_uaf(void)
    > 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();
    >
    > --
    > 2.29.2.729.g45daf8777d-goog
    >

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