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author | Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com> | 2023-01-29 05:14:35 +0300 |
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committer | Andrew Morton <akpm@linux-foundation.org> | 2023-02-10 03:51:40 +0300 |
commit | 8f17febb34ceb464e3ff99e9436d0ae3f47b4862 (patch) | |
tree | 056b5860bec0252c27d4bcb0315a2f11a0e4f820 /mm/kasan/kasan.h | |
parent | c2fdc235300a027adc04a41b383bd78ab5da56f4 (diff) | |
download | linux-8f17febb34ceb464e3ff99e9436d0ae3f47b4862.tar.xz |
kasan: infer allocation size by scanning metadata
Make KASAN scan metadata to infer the requested allocation size instead of
printing cache->object_size.
This patch fixes confusing slab-out-of-bounds reports as reported in:
https://bugzilla.kernel.org/show_bug.cgi?id=216457
As an example of the confusing behavior, the report below hints that the
allocation size was 192, while the kernel actually called kmalloc(184):
==================================================================
BUG: KASAN: slab-out-of-bounds in _find_next_bit+0x143/0x160 lib/find_bit.c:109
Read of size 8 at addr ffff8880175766b8 by task kworker/1:1/26
...
The buggy address belongs to the object at ffff888017576600
which belongs to the cache kmalloc-192 of size 192
The buggy address is located 184 bytes inside of
192-byte region [ffff888017576600, ffff8880175766c0)
...
Memory state around the buggy address:
ffff888017576580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff888017576600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888017576680: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
^
ffff888017576700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888017576780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
With this patch, the report shows:
==================================================================
...
The buggy address belongs to the object at ffff888017576600
which belongs to the cache kmalloc-192 of size 192
The buggy address is located 0 bytes to the right of
allocated 184-byte region [ffff888017576600, ffff8880175766b8)
...
==================================================================
Also report slab use-after-free bugs as "slab-use-after-free" and print
"freed" instead of "allocated" in the report when describing the accessed
memory region.
Also improve the metadata-related comment in kasan_find_first_bad_addr
and use addr_has_metadata across KASAN code instead of open-coding
KASAN_SHADOW_START checks.
[akpm@linux-foundation.org: fix printk warning]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216457
Link: https://lkml.kernel.org/r/20230129021437.18812-1-Kuan-Ying.Lee@mediatek.com
Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Co-developed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Qun-Wei Lin <qun-wei.lin@mediatek.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/kasan/kasan.h')
-rw-r--r-- | mm/kasan/kasan.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 32413f22aa82..308fb70fd40a 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -207,6 +207,7 @@ struct kasan_report_info { void *first_bad_addr; struct kmem_cache *cache; void *object; + size_t alloc_size; /* Filled in by the mode-specific reporting code. */ const char *bug_type; @@ -323,6 +324,7 @@ static inline bool addr_has_metadata(const void *addr) #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */ void *kasan_find_first_bad_addr(void *addr, size_t size); +size_t kasan_get_alloc_size(void *object, struct kmem_cache *cache); void kasan_complete_mode_report_info(struct kasan_report_info *info); void kasan_metadata_fetch_row(char *buffer, void *row); |