==================================================================
BUG: KASAN: slab-out-of-bounds in vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3275
Read of size 1 at addr ffff88809ec77fb6 by task syz-executor.3/14435

CPU: 0 PID: 14435 Comm: syz-executor.3 Not tainted 5.7.0-rc3-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 14435:
 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
 __vfs_write+0xa7/0x710 fs/read_write.c:495
 vfs_write+0x274/0x580 fs/read_write.c:559
 ksys_write+0x11b/0x220 fs/read_write.c:612
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 2727:
 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]
 kmem_cache_free_bulk+0x122/0x1d0 mm/slab.c:3721
 kfree_bulk include/linux/slab.h:412 [inline]
 kfree_rcu_work+0x1c7/0x3a0 kernel/rcu/tree.c:2859
 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:352

The buggy address belongs to the object at ffff88809ec77f80
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 54 bytes inside of
 64-byte region [ffff88809ec77f80, ffff88809ec77fc0)
The buggy address belongs to the page:
page:ffffea00027b1dc0 refcount:1 mapcount:0 mapping:00000000fe38f894 index:0xffff88809ec77100
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea000214b208 ffffea0002640588 ffff8880aa400380
raw: ffff88809ec77100 ffff88809ec77000 000000010000000d 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809ec77e80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88809ec77f00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff88809ec77f80: 00 00 00 00 00 00 06 fc fc fc fc fc fc fc fc fc
                                     ^
 ffff88809ec78000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809ec78080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================