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kasan: ensure poisoning size alignment

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A previous changes d99f6a10c1 ("kasan: don't round_up too much")
attempted to simplify the code by adding a round_up(size) call into
kasan_poison().  While this allows to have less round_up() calls around
the code, this results in round_up() being called multiple times.

This patch removes round_up() of size from kasan_poison() and ensures that
all callers round_up() the size explicitly.  This patch also adds
WARN_ON() alignment checks for address and size to kasan_poison() and
kasan_unpoison().

Link: https://lkml.kernel.org/r/3ffe8d4a246ae67a8b5e91f65bf98cd7cba9d7b9.1612546384.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.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: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.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>
This commit is contained in:
Andrey Konovalov 2021-02-25 17:20:27 -08:00 • committed by Linus Torvalds
parent d12d9ad816
commit cde8a7eb77
3 changed files with 48 additions and 31 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
mm/kasan/common.c
View file

@ -261,7 +261,8 @@ void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
{
kasan_poison(object, cache->object_size, KASAN_KMALLOC_REDZONE);
kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
KASAN_KMALLOC_REDZONE);
}
/*
@ -348,7 +349,8 @@ static bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
return true;
}
kasan_poison(object, cache->object_size, KASAN_KMALLOC_FREE);
kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
KASAN_KMALLOC_FREE);
if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine))
return false;
@ -490,7 +492,8 @@ static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object,
/* Poison the aligned part of the redzone. */
redzone_start = round_up((unsigned long)(object + size),
KASAN_GRANULE_SIZE);
redzone_end = (unsigned long)object + cache->object_size;
redzone_end = round_up((unsigned long)(object + cache->object_size),
KASAN_GRANULE_SIZE);
kasan_poison((void *)redzone_start, redzone_end - redzone_start,
KASAN_KMALLOC_REDZONE);

33
mm/kasan/kasan.h
View file

@ -330,30 +330,37 @@ static inline u8 kasan_random_tag(void) { return 0; }
#ifdef CONFIG_KASAN_HW_TAGS
static inline void kasan_poison(const void *address, size_t size, u8 value)
static inline void kasan_poison(const void *addr, size_t size, u8 value)
{
address = kasan_reset_tag(address);
addr = kasan_reset_tag(addr);
/* Skip KFENCE memory if called explicitly outside of sl*b. */
if (is_kfence_address(address))
if (is_kfence_address(addr))
return;
hw_set_mem_tag_range((void *)address,
round_up(size, KASAN_GRANULE_SIZE), value);
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);
}
static inline void kasan_unpoison(const void *address, size_t size)
static inline void kasan_unpoison(const void *addr, size_t size)
{
u8 tag = get_tag(address);
u8 tag = get_tag(addr);
address = kasan_reset_tag(address);
addr = kasan_reset_tag(addr);
/* Skip KFENCE memory if called explicitly outside of sl*b. */
if (is_kfence_address(address))
if (is_kfence_address(addr))
return;
hw_set_mem_tag_range((void *)address,
round_up(size, KASAN_GRANULE_SIZE), tag);
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);
}
static inline bool kasan_byte_accessible(const void *addr)
@ -370,7 +377,7 @@ static inline bool kasan_byte_accessible(const void *addr)
/**
* kasan_poison - mark the memory range as unaccessible
* @addr - range start address, must be aligned to KASAN_GRANULE_SIZE
* @size - range size
* @size - range size, must be aligned to KASAN_GRANULE_SIZE
* @value - value that's written to metadata for the range
*
* The size gets aligned to KASAN_GRANULE_SIZE before marking the range.
@ -380,7 +387,7 @@ void kasan_poison(const void *addr, size_t size, u8 value);
/**
* kasan_unpoison - mark the memory range as accessible
* @addr - range start address, must be aligned to KASAN_GRANULE_SIZE
* @size - range size
* @size - range size, can be unaligned
*
* For the tag-based modes, the @size gets aligned to KASAN_GRANULE_SIZE before
* marking the range.

37
mm/kasan/shadow.c
View file

@ -69,7 +69,7 @@ void *memcpy(void *dest, const void *src, size_t len)
return __memcpy(dest, src, len);
}
void kasan_poison(const void *address, size_t size, u8 value)
void kasan_poison(const void *addr, size_t size, u8 value)
{
void *shadow_start, *shadow_end;
@ -78,55 +78,62 @@ void kasan_poison(const void *address, size_t size, u8 value)
* some of the callers (e.g. kasan_poison_object_data) pass tagged
* addresses to this function.
*/
address = kasan_reset_tag(address);
addr = kasan_reset_tag(addr);
/* Skip KFENCE memory if called explicitly outside of sl*b. */
if (is_kfence_address(address))
if (is_kfence_address(addr))
return;
size = round_up(size, KASAN_GRANULE_SIZE);
shadow_start = kasan_mem_to_shadow(address);
shadow_end = kasan_mem_to_shadow(address + size);
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
if (WARN_ON(size & KASAN_GRANULE_MASK))
return;
shadow_start = kasan_mem_to_shadow(addr);
shadow_end = kasan_mem_to_shadow(addr + size);
__memset(shadow_start, value, shadow_end - shadow_start);
}
EXPORT_SYMBOL(kasan_poison);
#ifdef CONFIG_KASAN_GENERIC
void kasan_poison_last_granule(const void *address, size_t size)
void kasan_poison_last_granule(const void *addr, size_t size)
{
if (size & KASAN_GRANULE_MASK) {
u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
u8 *shadow = (u8 *)kasan_mem_to_shadow(addr + size);
*shadow = size & KASAN_GRANULE_MASK;
}
}
#endif
void kasan_unpoison(const void *address, size_t size)
void kasan_unpoison(const void *addr, size_t size)
{
u8 tag = get_tag(address);
u8 tag = get_tag(addr);
/*
* Perform shadow offset calculation based on untagged address, as
* some of the callers (e.g. kasan_unpoison_object_data) pass tagged
* addresses to this function.
*/
address = kasan_reset_tag(address);
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(address))
if (is_kfence_address(addr))
return;
/* Unpoison round_up(size, KASAN_GRANULE_SIZE) bytes. */
kasan_poison(address, size, tag);
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
/* Unpoison all granules that cover the object. */
kasan_poison(addr, round_up(size, KASAN_GRANULE_SIZE), tag);
/* Partially poison the last granule for the generic mode. */
if (IS_ENABLED(CONFIG_KASAN_GENERIC))
kasan_poison_last_granule(address, size);
kasan_poison_last_granule(addr, size);
}
#ifdef CONFIG_MEMORY_HOTPLUG