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kasan: fix null pointer dereference in kasan_record_aux_stack

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Syzbot reported the following [1]:

  BUG: kernel NULL pointer dereference, address: 0000000000000008
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 2d993067 P4D 2d993067 PUD 19a3c067 PMD 0
  Oops: 0000 [#1] PREEMPT SMP KASAN
  CPU: 1 PID: 3852 Comm: kworker/1:2 Not tainted 5.10.0-syzkaller #0
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
  Workqueue: events free_ipc
  RIP: 0010:kasan_record_aux_stack+0x77/0xb0

Add null checking slab object from kasan_get_alloc_meta() in order to
avoid null pointer dereference.

[1] https://syzkaller.appspot.com/x/log.txt?x=10a82a50d00000

Link: https://lkml.kernel.org/r/20201228080018.23041-1-walter-zh.wu@mediatek.com
Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Konovalov <andreyknvl@google.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:
Walter Wu 2020-12-29 15:14:46 -08:00 committed by Linus Torvalds
parent 111fe7186b
commit 13384f6125
1 changed files with 2 additions and 0 deletions
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2
mm/kasan/generic.c
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@ -337,6 +337,8 @@ void kasan_record_aux_stack(void *addr)
cache = page->slab_cache;
object = nearest_obj(cache, page, addr);
alloc_meta = kasan_get_alloc_meta(cache, object);
if (!alloc_meta)
return;
alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0];
alloc_meta->aux_stack[0] = kasan_save_stack(GFP_NOWAIT);