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BUG: KASAN: slab-out-of-bounds in vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3294
Read of size 1 at addr ffff88804dcdd2c2 by task syz-executor.4/10455

CPU: 0 PID: 10455 Comm: syz-executor.4 Not tainted 5.7.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1e9/0x30e lib/dump_stack.c:118
 print_address_description+0x74/0x5c0 mm/kasan/report.c:382
 __kasan_report+0x103/0x1a0 mm/kasan/report.c:511
 kasan_report+0x4d/0x80 mm/kasan/common.c:625

Allocated by task 10455:
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc+0x114/0x160 mm/kasan/common.c:495
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc_track_caller+0x249/0x320 mm/slab.c:3671
 memdup_user_nul+0x26/0xf0 mm/util.c:259
 smk_set_cipso+0xff/0x6a0 security/smack/smackfs.c:859
 do_loop_readv_writev fs/read_write.c:718 [inline]
 do_iter_write+0x402/0x540 fs/read_write.c:1001
 vfs_writev fs/read_write.c:1072 [inline]
 do_writev+0x23f/0x4a0 fs/read_write.c:1115
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 15058:
 save_stack mm/kasan/common.c:49 [inline]
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0x125/0x190 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x220 mm/slab.c:3757
 batadv_mcast_mla_list_free net/batman-adv/multicast.c:671 [inline]
 __batadv_mcast_mla_update net/batman-adv/multicast.c:926 [inline]
 batadv_mcast_mla_update+0x345d/0x3820 net/batman-adv/multicast.c:948
 process_one_work+0x76e/0xfd0 kernel/workqueue.c:2268
 worker_thread+0xa7f/0x1450 kernel/workqueue.c:2414
 kthread+0x353/0x380 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

The buggy address belongs to the object at ffff88804dcdd2c0
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 2 bytes inside of
 32-byte region [ffff88804dcdd2c0, ffff88804dcdd2e0)
The buggy address belongs to the page:
page:ffffea0001373740 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88804dcddfc1
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea000125e9c8 ffffea00029375c8 ffff8880aa4001c0
raw: ffff88804dcddfc1 ffff88804dcdd000 000000010000003f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88804dcdd180: 05 fc fc fc fc fc fc fc 05 fc fc fc fc fc fc fc
 ffff88804dcdd200: 00 00 00 00 fc fc fc fc fb fb fb fb fc fc fc fc
>ffff88804dcdd280: fb fb fb fb fc fc fc fc 02 fc fc fc fc fc fc fc
                                           ^
 ffff88804dcdd300: 05 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc
 ffff88804dcdd380: 05 fc fc fc fc fc fc fc 05 fc fc fc fc fc fc fc
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