diff options
Diffstat (limited to 'mm/kasan')
| -rw-r--r-- | mm/kasan/common.c | 25 | ||||
| -rw-r--r-- | mm/kasan/kasan_test_c.c | 8 |
2 files changed, 26 insertions, 7 deletions
diff --git a/mm/kasan/common.c b/mm/kasan/common.c index ed4873e18c75..9142964ab9c9 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -230,16 +230,12 @@ static bool check_slab_allocation(struct kmem_cache *cache, void *object, } static inline void poison_slab_object(struct kmem_cache *cache, void *object, - bool init, bool still_accessible) + bool init) { void *tagged_object = object; object = kasan_reset_tag(object); - /* RCU slabs could be legally used after free within the RCU period. */ - if (unlikely(still_accessible)) - return; - kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE), KASAN_SLAB_FREE, init); @@ -261,7 +257,22 @@ bool __kasan_slab_free(struct kmem_cache *cache, void *object, bool init, if (!kasan_arch_is_ready() || is_kfence_address(object)) return false; - poison_slab_object(cache, object, init, still_accessible); + /* + * If this point is reached with an object that must still be + * accessible under RCU, we can't poison it; in that case, also skip the + * quarantine. This should mostly only happen when CONFIG_SLUB_RCU_DEBUG + * has been disabled manually. + * + * Putting the object on the quarantine wouldn't help catch UAFs (since + * we can't poison it here), and it would mask bugs caused by + * SLAB_TYPESAFE_BY_RCU users not being careful enough about object + * reuse; so overall, putting the object into the quarantine here would + * be counterproductive. + */ + if (still_accessible) + return false; + + poison_slab_object(cache, object, init); /* * If the object is put into quarantine, do not let slab put the object @@ -519,7 +530,7 @@ bool __kasan_mempool_poison_object(void *ptr, unsigned long ip) if (check_slab_allocation(slab->slab_cache, ptr, ip)) return false; - poison_slab_object(slab->slab_cache, ptr, false, false); + poison_slab_object(slab->slab_cache, ptr, false); return true; } diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c index 5f922dd38ffa..2aa12dfa427a 100644 --- a/mm/kasan/kasan_test_c.c +++ b/mm/kasan/kasan_test_c.c @@ -1977,6 +1977,11 @@ static void rust_uaf(struct kunit *test) KUNIT_EXPECT_KASAN_FAIL(test, kasan_test_rust_uaf()); } +/* + * copy_to_kernel_nofault() is an internal helper available when + * kasan_test is built-in, so it must not be visible to loadable modules. + */ +#ifndef MODULE static void copy_to_kernel_nofault_oob(struct kunit *test) { char *ptr; @@ -2011,6 +2016,7 @@ static void copy_to_kernel_nofault_oob(struct kunit *test) kfree(ptr); } +#endif /* !MODULE */ static void copy_user_test_oob(struct kunit *test) { @@ -2131,7 +2137,9 @@ static struct kunit_case kasan_kunit_test_cases[] = { KUNIT_CASE(match_all_not_assigned), KUNIT_CASE(match_all_ptr_tag), KUNIT_CASE(match_all_mem_tag), +#ifndef MODULE KUNIT_CASE(copy_to_kernel_nofault_oob), +#endif KUNIT_CASE(rust_uaf), KUNIT_CASE(copy_user_test_oob), {} |