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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>
This commit is contained in:
Andrey Konovalov 2020-12-22 12:00:46 -08:00 committed by Linus Torvalds
parent ffcc5cea46
commit 2cdbed6349
4 changed files with 19 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
mm/kasan/common.c
View File

@ -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;
}

7
mm/kasan/generic.c
View File

@ -187,6 +187,13 @@ 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);

2
mm/kasan/kasan.h
View File

@ -166,6 +166,8 @@ void unpoison_range(const void *address, size_t size);
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);

9
mm/kasan/sw_tags.c
View File

@ -121,6 +121,15 @@ 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)));
return (shadow_byte == KASAN_TAG_INVALID) ||
(tag != KASAN_TAG_KERNEL && tag != shadow_byte);
}
#define DEFINE_HWASAN_LOAD_STORE(size) \
void __hwasan_load##size##_noabort(unsigned long addr) \
{ \