This is a preparatory commit for the upcoming addition of a new hardware tag-based (MTE-based) KASAN mode.
For software KASAN modes the check is based on the value in the shadow memory. Hardware tag-based KASAN won't be using shadow, so hide the implementation of the check in check_invalid_free(). No functional changes for software modes. Signed-off-by: Andrey Konovalov <[email protected]> --- mm/kasan/common.c | 19 +------------------ mm/kasan/generic.c | 7 +++++++ mm/kasan/kasan.h | 2 ++ mm/kasan/tags.c | 12 ++++++++++++ 4 files changed, 22 insertions(+), 18 deletions(-) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 43a927e70067..a2321d35390e 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -277,25 +277,9 @@ void * __must_check kasan_init_slab_obj(struct kmem_cache *cache, return (void *)object; } -static inline bool shadow_invalid(u8 tag, s8 shadow_byte) -{ - if (IS_ENABLED(CONFIG_KASAN_GENERIC)) - return shadow_byte < 0 || - shadow_byte >= KASAN_GRANULE_SIZE; - - /* else CONFIG_KASAN_SW_TAGS: */ - if ((u8)shadow_byte == KASAN_TAG_INVALID) - return true; - if ((tag != KASAN_TAG_KERNEL) && (tag != (u8)shadow_byte)) - return true; - - return false; -} - static bool __kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip, bool quarantine) { - s8 shadow_byte; u8 tag; void *tagged_object; unsigned long rounded_up_size; @@ -314,8 +298,7 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object, if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU)) return false; - shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object)); - if (shadow_invalid(tag, shadow_byte)) { + if (check_invalid_free(tagged_object)) { kasan_report_invalid_free(tagged_object, ip); return true; } diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index f6d68aa9872f..73f4d786ad5d 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -192,6 +192,13 @@ bool check_memory_region(unsigned long addr, size_t size, bool write, return check_memory_region_inline(addr, size, write, ret_ip); } +bool check_invalid_free(void *addr) +{ + s8 shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr)); + + return shadow_byte < 0 || shadow_byte >= KASAN_GRANULE_SIZE; +} + void kasan_cache_shrink(struct kmem_cache *cache) { quarantine_remove_cache(cache); diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index c31e2c739301..cf6a135860f2 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -163,6 +163,8 @@ void kasan_poison_memory(const void *address, size_t size, u8 value); bool check_memory_region(unsigned long addr, size_t size, bool write, unsigned long ret_ip); +bool check_invalid_free(void *addr); + void *find_first_bad_addr(void *addr, size_t size); const char *get_bug_type(struct kasan_access_info *info); diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c index 4d5a1fe8251f..feb42c1763b8 100644 --- a/mm/kasan/tags.c +++ b/mm/kasan/tags.c @@ -126,6 +126,18 @@ bool check_memory_region(unsigned long addr, size_t size, bool write, return true; } +bool check_invalid_free(void *addr) +{ + u8 tag = get_tag(addr); + u8 shadow_byte = READ_ONCE(*(u8 *)kasan_mem_to_shadow(reset_tag(addr))); + + if (shadow_byte == KASAN_TAG_INVALID) + return true; + if (tag != KASAN_TAG_KERNEL && tag != shadow_byte) + return true; + return false; +} + #define DEFINE_HWASAN_LOAD_STORE(size) \ void __hwasan_load##size##_noabort(unsigned long addr) \ { \ -- 2.28.0.220.ged08abb693-goog
