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kasan: improve slab object description 

Changes slab object description from:

  Object at ffff880068388540, in cache kmalloc-128 size: 128

to:

  The buggy address belongs to the object at ffff880068388540
   which belongs to the cache kmalloc-128 of size 128
  The buggy address is located 123 bytes inside of
   128-byte region [ffff880068388540, ffff8800683885c0)

Makes it more explanatory and adds information about relative offset of
the accessed address to the start of the object.

Link: http://lkml.kernel.org/r/20170302134851.101218-7-andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.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 2017-05-03 14:56:41 -07:00 committed by Linus Torvalds
parent 7f0a84c23b
commit 0c06f1f86c
1 changed files with 43 additions and 12 deletions
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55
mm/kasan/report.c
View File

@ -198,18 +198,49 @@ static struct page *addr_to_page(const void *addr)
return NULL; return NULL;
} }
static void describe_object(struct kmem_cache *cache, void *object) static void describe_object_addr(struct kmem_cache *cache, void *object,
const void *addr)
{
unsigned long access_addr = (unsigned long)addr;
unsigned long object_addr = (unsigned long)object;
const char *rel_type;
int rel_bytes;
pr_err("The buggy address belongs to the object at %p\n"
" which belongs to the cache %s of size %d\n",
object, cache->name, cache->object_size);
if (!addr)
return;
if (access_addr < object_addr) {
rel_type = "to the left";
rel_bytes = object_addr - access_addr;
} else if (access_addr >= object_addr + cache->object_size) {
rel_type = "to the right";
rel_bytes = access_addr - (object_addr + cache->object_size);
} else {
rel_type = "inside";
rel_bytes = access_addr - object_addr;
}
pr_err("The buggy address is located %d bytes %s of\n"
" %d-byte region [%p, %p)\n",
rel_bytes, rel_type, cache->object_size, (void *)object_addr,
(void *)(object_addr + cache->object_size));
}
static void describe_object(struct kmem_cache *cache, void *object,
const void *addr)
{ {
struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
pr_err("Object at %p, in cache %s size: %d\n", object, cache->name, if (cache->flags & SLAB_KASAN) {
cache->object_size); print_track(&alloc_info->alloc_track, "Allocated");
print_track(&alloc_info->free_track, "Freed");
}
if (!(cache->flags & SLAB_KASAN)) describe_object_addr(cache, object, addr);
return;
print_track(&alloc_info->alloc_track, "Allocated");
print_track(&alloc_info->free_track, "Freed");
} }
void kasan_report_double_free(struct kmem_cache *cache, void *object, void kasan_report_double_free(struct kmem_cache *cache, void *object,
@ -221,13 +252,13 @@ void kasan_report_double_free(struct kmem_cache *cache, void *object,
pr_err("BUG: Double free or freeing an invalid pointer\n"); pr_err("BUG: Double free or freeing an invalid pointer\n");
pr_err("Unexpected shadow byte: 0x%hhX\n", shadow); pr_err("Unexpected shadow byte: 0x%hhX\n", shadow);
dump_stack(); dump_stack();
describe_object(cache, object); describe_object(cache, object, NULL);
kasan_end_report(&flags); kasan_end_report(&flags);
} }
static void print_address_description(struct kasan_access_info *info) static void print_address_description(struct kasan_access_info *info)
{ {
const void *addr = info->access_addr; void *addr = (void *)info->access_addr;
struct page *page = addr_to_page(addr); struct page *page = addr_to_page(addr);
if (page) if (page)
@ -237,9 +268,9 @@ static void print_address_description(struct kasan_access_info *info)
if (page && PageSlab(page)) { if (page && PageSlab(page)) {
struct kmem_cache *cache = page->slab_cache; struct kmem_cache *cache = page->slab_cache;
void *object = nearest_obj(cache, page, (void *)addr); void *object = nearest_obj(cache, page, addr);
describe_object(cache, object); describe_object(cache, object, addr);
} }
if (kernel_or_module_addr(addr)) { if (kernel_or_module_addr(addr)) {