| Message ID | 20250318015926.1629748-1-harry.yoo@oracle.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [mm-unstable] mm/kasan: use SLAB_NO_MERGE flag instead of an empty constructor | expand |
On Tue, Mar 18, 2025 at 2:59 AM Harry Yoo <harry.yoo@oracle.com> wrote: > > Use SLAB_NO_MERGE flag to prevent merging instead of providing an > empty constructor. Using an empty constructor in this manner is an abuse > of slab interface. This code predated the existence of SLAB_NO_MERGE. Thanks for fixing this! > > Signed-off-by: Harry Yoo <harry.yoo@oracle.com> Reviewed-by: Alexander Potapenko <glider@google.com>
On Tue, Mar 18, 2025 at 2:59 AM Harry Yoo <harry.yoo@oracle.com> wrote: > > Use SLAB_NO_MERGE flag to prevent merging instead of providing an > empty constructor. Using an empty constructor in this manner is an abuse > of slab interface. > > The SLAB_NO_MERGE flag should be used with caution, but in this case, > it is acceptable as the cache is intended solely for debugging purposes. > > No functional changes intended. > > Signed-off-by: Harry Yoo <harry.yoo@oracle.com> > --- > mm/kasan/kasan_test_c.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c > index 59d673400085..3ea317837c2d 100644 > --- a/mm/kasan/kasan_test_c.c > +++ b/mm/kasan/kasan_test_c.c > @@ -1073,14 +1073,11 @@ static void kmem_cache_rcu_uaf(struct kunit *test) > kmem_cache_destroy(cache); > } > > -static void empty_cache_ctor(void *object) { } > - > static void kmem_cache_double_destroy(struct kunit *test) > { > struct kmem_cache *cache; > > - /* Provide a constructor to prevent cache merging. */ > - cache = kmem_cache_create("test_cache", 200, 0, 0, empty_cache_ctor); > + cache = kmem_cache_create("test_cache", 200, 0, SLAB_NO_MERGE, NULL); > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cache); > kmem_cache_destroy(cache); > KUNIT_EXPECT_KASAN_FAIL(test, kmem_cache_destroy(cache)); > -- > 2.43.0 > Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Thanks!
diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c index 59d673400085..3ea317837c2d 100644 --- a/mm/kasan/kasan_test_c.c +++ b/mm/kasan/kasan_test_c.c @@ -1073,14 +1073,11 @@ static void kmem_cache_rcu_uaf(struct kunit *test) kmem_cache_destroy(cache); } -static void empty_cache_ctor(void *object) { } - static void kmem_cache_double_destroy(struct kunit *test) { struct kmem_cache *cache; - /* Provide a constructor to prevent cache merging. */ - cache = kmem_cache_create("test_cache", 200, 0, 0, empty_cache_ctor); + cache = kmem_cache_create("test_cache", 200, 0, SLAB_NO_MERGE, NULL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cache); kmem_cache_destroy(cache); KUNIT_EXPECT_KASAN_FAIL(test, kmem_cache_destroy(cache));
Use SLAB_NO_MERGE flag to prevent merging instead of providing an empty constructor. Using an empty constructor in this manner is an abuse of slab interface. The SLAB_NO_MERGE flag should be used with caution, but in this case, it is acceptable as the cache is intended solely for debugging purposes. No functional changes intended. Signed-off-by: Harry Yoo <harry.yoo@oracle.com> --- mm/kasan/kasan_test_c.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)