kasan: hide invalid free check implementation
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(). Also simplify the code for software tag-based mode. No functional changes for software modes. Link: https://lkml.kernel.org/r/d01534a4b977f97d87515dc590e6348e1406de81.1606161801.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Alexander Potapenko <glider@google.com> Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Branislav Rankov <Branislav.Rankov@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Kevin Brodsky <kevin.brodsky@arm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -277,25 +277,9 @@ void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
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return (void *)object;
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}
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static inline bool shadow_invalid(u8 tag, s8 shadow_byte)
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{
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if (IS_ENABLED(CONFIG_KASAN_GENERIC))
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return shadow_byte < 0 ||
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shadow_byte >= KASAN_GRANULE_SIZE;
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/* else CONFIG_KASAN_SW_TAGS: */
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if ((u8)shadow_byte == KASAN_TAG_INVALID)
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return true;
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if ((tag != KASAN_TAG_KERNEL) && (tag != (u8)shadow_byte))
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return true;
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return false;
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}
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static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
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unsigned long ip, bool quarantine)
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{
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s8 shadow_byte;
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u8 tag;
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void *tagged_object;
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unsigned long rounded_up_size;
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@ -314,8 +298,7 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
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if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
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return false;
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shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
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if (shadow_invalid(tag, shadow_byte)) {
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if (check_invalid_free(tagged_object)) {
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kasan_report_invalid_free(tagged_object, ip);
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return true;
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}
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@ -187,6 +187,13 @@ bool check_memory_region(unsigned long addr, size_t size, bool write,
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return check_memory_region_inline(addr, size, write, ret_ip);
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}
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bool check_invalid_free(void *addr)
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{
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s8 shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr));
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return shadow_byte < 0 || shadow_byte >= KASAN_GRANULE_SIZE;
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}
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void kasan_cache_shrink(struct kmem_cache *cache)
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{
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quarantine_remove_cache(cache);
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@ -166,6 +166,8 @@ void unpoison_range(const void *address, size_t size);
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bool check_memory_region(unsigned long addr, size_t size, bool write,
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unsigned long ret_ip);
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bool check_invalid_free(void *addr);
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void *find_first_bad_addr(void *addr, size_t size);
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const char *get_bug_type(struct kasan_access_info *info);
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@ -121,6 +121,15 @@ bool check_memory_region(unsigned long addr, size_t size, bool write,
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return true;
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}
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bool check_invalid_free(void *addr)
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{
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u8 tag = get_tag(addr);
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u8 shadow_byte = READ_ONCE(*(u8 *)kasan_mem_to_shadow(reset_tag(addr)));
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return (shadow_byte == KASAN_TAG_INVALID) ||
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(tag != KASAN_TAG_KERNEL && tag != shadow_byte);
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}
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#define DEFINE_HWASAN_LOAD_STORE(size) \
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void __hwasan_load##size##_noabort(unsigned long addr) \
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{ \
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