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kasan: clean up is_kfence_address checks

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1. Do not untag addresses that are passed to is_kfence_address: it
   tolerates tagged addresses.

2. Move is_kfence_address checks from internal KASAN functions
   (kasan_poison/unpoison, etc.) to external-facing ones.

   Note that kasan_poison/unpoison are never called outside of KASAN/slab
   code anymore; the comment is wrong, so drop it.

3. Simplify/reorganize the code around the updated checks.

Link: https://lkml.kernel.org/r/1065732315ef4e141b6177d8f612232d4d5bc0ab.1703188911.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2023-12-21 21:04:48 +01:00 committed by Andrew Morton
parent 1a55836a1b
commit 99f3fe416c
3 changed files with 19 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
mm/kasan/common.c
View File

@ -79,6 +79,9 @@ EXPORT_SYMBOL(kasan_disable_current);
void __kasan_unpoison_range(const void *address, size_t size)
{
if (is_kfence_address(address))
return;
kasan_unpoison(address, size, false);
}
@ -218,9 +221,6 @@ static inline bool poison_slab_object(struct kmem_cache *cache, void *object,
tagged_object = object;
object = kasan_reset_tag(object);
if (is_kfence_address(object))
return false;
if (unlikely(nearest_obj(cache, virt_to_slab(object), object) != object)) {
kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_INVALID_FREE);
return true;
@ -247,7 +247,12 @@ static inline bool poison_slab_object(struct kmem_cache *cache, void *object,
bool __kasan_slab_free(struct kmem_cache *cache, void *object,
unsigned long ip, bool init)
{
bool buggy_object = poison_slab_object(cache, object, ip, init);
bool buggy_object;
if (is_kfence_address(object))
return false;
buggy_object = poison_slab_object(cache, object, ip, init);
return buggy_object ? true : kasan_quarantine_put(cache, object);
}
@ -359,7 +364,7 @@ void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object
if (unlikely(object == NULL))
return NULL;
if (is_kfence_address(kasan_reset_tag(object)))
if (is_kfence_address(object))
return (void *)object;
/* The object has already been unpoisoned by kasan_slab_alloc(). */
@ -417,7 +422,7 @@ void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flag
if (unlikely(object == ZERO_SIZE_PTR))
return (void *)object;
if (is_kfence_address(kasan_reset_tag(object)))
if (is_kfence_address(object))
return (void *)object;
/*
@ -483,6 +488,9 @@ bool __kasan_mempool_poison_object(void *ptr, unsigned long ip)
return true;
}
if (is_kfence_address(ptr))
return false;
slab = folio_slab(folio);
return !poison_slab_object(slab->slab_cache, ptr, ip, false);
}
@ -492,9 +500,6 @@ void __kasan_mempool_unpoison_object(void *ptr, size_t size, unsigned long ip)
struct slab *slab;
gfp_t flags = 0; /* Might be executing under a lock. */
if (is_kfence_address(kasan_reset_tag(ptr)))
return;
slab = virt_to_slab(ptr);
/*
@ -507,6 +512,9 @@ void __kasan_mempool_unpoison_object(void *ptr, size_t size, unsigned long ip)
return;
}
if (is_kfence_address(ptr))
return;
/* Unpoison the object and save alloc info for non-kmalloc() allocations. */
unpoison_slab_object(slab->slab_cache, ptr, size, flags);

16
mm/kasan/kasan.h
View File

@ -466,35 +466,23 @@ static inline u8 kasan_random_tag(void) { return 0; }
static inline void kasan_poison(const void *addr, size_t size, u8 value, bool init)
{
addr = kasan_reset_tag(addr);
/* Skip KFENCE memory if called explicitly outside of sl*b. */
if (is_kfence_address(addr))
return;
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
if (WARN_ON(size & KASAN_GRANULE_MASK))
return;
hw_set_mem_tag_range((void *)addr, size, value, init);
hw_set_mem_tag_range(kasan_reset_tag(addr), size, value, init);
}
static inline void kasan_unpoison(const void *addr, size_t size, bool init)
{
u8 tag = get_tag(addr);
addr = kasan_reset_tag(addr);
/* Skip KFENCE memory if called explicitly outside of sl*b. */
if (is_kfence_address(addr))
return;
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
size = round_up(size, KASAN_GRANULE_SIZE);
hw_set_mem_tag_range((void *)addr, size, tag, init);
hw_set_mem_tag_range(kasan_reset_tag(addr), size, tag, init);
}
static inline bool kasan_byte_accessible(const void *addr)

12
mm/kasan/shadow.c
View File

@ -135,10 +135,6 @@ void kasan_poison(const void *addr, size_t size, u8 value, bool init)
*/
addr = kasan_reset_tag(addr);
/* Skip KFENCE memory if called explicitly outside of sl*b. */
if (is_kfence_address(addr))
return;
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
if (WARN_ON(size & KASAN_GRANULE_MASK))
@ -175,14 +171,6 @@ void kasan_unpoison(const void *addr, size_t size, bool init)
*/
addr = kasan_reset_tag(addr);
/*
* Skip KFENCE memory if called explicitly outside of sl*b. Also note
* that calls to ksize(), where size is not a multiple of machine-word
* size, would otherwise poison the invalid portion of the word.
*/
if (is_kfence_address(addr))
return;
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;