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BUG: KASAN: slab-out-of-bounds in vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3294
Read of size 1 at addr ffff888093f5698b by task syz-executor.0/28525

CPU: 0 PID: 28525 Comm: syz-executor.0 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 28525:
 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 0:
 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
 security_cred_free+0xbf/0x100 security/security.c:1599
 put_cred_rcu+0xca/0x350 kernel/cred.c:114
 rcu_do_batch kernel/rcu/tree.c:2206 [inline]
 rcu_core+0x816/0x1120 kernel/rcu/tree.c:2433
 __do_softirq+0x268/0x80c kernel/softirq.c:292

The buggy address belongs to the object at ffff888093f56900
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 139 bytes inside of
 192-byte region [ffff888093f56900, ffff888093f569c0)
The buggy address belongs to the page:
page:ffffea00024fd580 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888093f56300
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00029c3408 ffffea00022cc7c8 ffff8880aa400000
raw: ffff888093f56300 ffff888093f56000 0000000100000008 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888093f56880: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888093f56900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888093f56980: 00 03 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                      ^
 ffff888093f56a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888093f56a80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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