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BUG: KASAN: slab-out-of-bounds in vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3321
Read of size 1 at addr ffff888090a73f70 by task syz-executor.3/11086

CPU: 0 PID: 11086 Comm: syz-executor.3 Not tainted 5.8.0-rc2-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+0x1f0/0x31e lib/dump_stack.c:118
 print_address_description+0x66/0x5a0 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report+0x132/0x1d0 mm/kasan/report.c:530
 vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3321
 sscanf+0x6c/0x90 lib/vsprintf.c:3527
 smk_set_cipso+0x374/0x6c0 security/smack/smackfs.c:908
 __vfs_write+0x9c/0x6e0 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+0x73/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cb19
Code: Bad RIP value.
RSP: 002b:00007f744a7cbc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000050e840 RCX: 000000000045cb19
RDX: 000000000000006f RSI: 0000000020000180 RDI: 0000000000000007
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000d49 R14: 00000000004cfa53 R15: 00007f744a7cc6d4

Allocated by task 11086:
 save_stack mm/kasan/common.c:48 [inline]
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc+0x103/0x140 mm/kasan/common.c:494
 __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/0x6c0 security/smack/smackfs.c:859
 __vfs_write+0x9c/0x6e0 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+0x73/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 3879:
 save_stack mm/kasan/common.c:48 [inline]
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0x114/0x170 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x220 mm/slab.c:3757
 kernfs_fop_release+0x1d8/0x2b0 fs/kernfs/file.c:779
 __fput+0x2f0/0x750 fs/file_table.c:281
 task_work_run+0x137/0x1c0 kernel/task_work.c:123
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:216 [inline]
 __prepare_exit_to_usermode+0x14c/0x1e0 arch/x86/entry/common.c:246
 do_syscall_64+0x7f/0xe0 arch/x86/entry/common.c:368
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff888090a73f00
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 112 bytes inside of
 128-byte region [ffff888090a73f00, ffff888090a73f80)
The buggy address belongs to the page:
page:ffffea0002429cc0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002881fc8 ffffea000246f048 ffff8880aa400700
raw: 0000000000000000 ffff888090a73000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888090a73e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888090a73e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888090a73f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc
                                                             ^
 ffff888090a73f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888090a74000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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