==================================================================
BUG: KASAN: slab-out-of-bounds in vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3275
Read of size 1 at addr ffff8880a2d9c83a by task syz-executor.4/8389

CPU: 0 PID: 8389 Comm: syz-executor.4 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 8389:
 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 2686:
 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
 free_work+0x66/0x90 mm/vmalloc.c:67
 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 ffff8880a2d9c800
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 58 bytes inside of
 64-byte region [ffff8880a2d9c800, ffff8880a2d9c840)
The buggy address belongs to the page:
page:ffffea00028b6700 refcount:1 mapcount:0 mapping:0000000064f200f6 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002549448 ffffea0002a43b08 ffff8880aa400380
raw: 0000000000000000 ffff8880a2d9c000 0000000100000020 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a2d9c700: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff8880a2d9c780: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff8880a2d9c800: 00 00 00 00 00 00 00 02 fc fc fc fc fc fc fc fc
                                        ^
 ffff8880a2d9c880: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
 ffff8880a2d9c900: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
==================================================================