==================================================================
BUG: KASAN: slab-out-of-bounds in vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3275
Read of size 1 at addr ffff888092700a42 by task syz-executor.1/12976

CPU: 1 PID: 12976 Comm: syz-executor.1 Not tainted 5.7.0-rc4-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 12976:
 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
 __kernel_write+0x120/0x350 fs/read_write.c:516
 write_pipe_buf+0xf9/0x150 fs/splice.c:809
 splice_from_pipe_feed fs/splice.c:512 [inline]
 __splice_from_pipe+0x329/0x870 fs/splice.c:636
 splice_from_pipe fs/splice.c:671 [inline]
 default_file_splice_write+0x112/0x1b0 fs/splice.c:821
 do_splice_from fs/splice.c:863 [inline]
 do_splice+0xdcd/0x18c0 fs/splice.c:1170
 __do_sys_splice fs/splice.c:1447 [inline]
 __se_sys_splice+0x172/0x230 fs/splice.c:1427
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 12614:
 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
 smk_import_entry+0x40f/0x560 security/smack/smack_access.c:578
 smk_fetch security/smack/smack_lsm.c:300 [inline]
 smack_d_instantiate+0x6e1/0xd90 security/smack/smack_lsm.c:3408
 security_d_instantiate+0xa5/0x100 security/security.c:1925
 d_instantiate_new+0x61/0x110 fs/dcache.c:1973
 ext4_add_nondir+0x1f6/0x260 fs/ext4/namei.c:2582
 ext4_symlink+0x8ba/0xef0 fs/ext4/namei.c:3364
 vfs_symlink+0x36f/0x520 fs/namei.c:3937
 do_symlinkat+0x18b/0x420 fs/namei.c:3964
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

The buggy address belongs to the object at ffff888092700a40
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 2 bytes inside of
 32-byte region [ffff888092700a40, ffff888092700a60)
The buggy address belongs to the page:
page:ffffea000249c000 refcount:1 mapcount:0 mapping:00000000496fc140 index:0xffff888092700fc1
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea000275f048 ffffea0002912548 ffff8880aa4001c0
raw: ffff888092700fc1 ffff888092700000 000000010000003d 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888092700900: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff888092700980: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff888092700a00: fb fb fb fb fc fc fc fc 02 fc fc fc fc fc fc fc
                                           ^
 ffff888092700a80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff888092700b00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================