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 Signed-off-by: Walter Wu <[email protected]> Suggested-by: Dmitry Vyukov <[email protected]> Cc: Andrey Ryabinin <[email protected]> CC: Dmitry Vyukov <[email protected]> CC: Andrey Konovalov <[email protected]> Cc: Alexander Potapenko <[email protected]> Cc: Andrew Morton <[email protected]> --- mm/kasan/generic.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index 1dd5a0f99372..5106b84b07d4 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -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); -- 2.18.0
