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BUG: KASAN: slab-out-of-bounds in vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3275
Read of size 1 at addr ffff8880a6a7b484 by task syz-executor.3/18470

CPU: 0 PID: 18470 Comm: syz-executor.3 Not tainted 5.6.0-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:374
 __kasan_report+0x14b/0x1c0 mm/kasan/report.c:506
 kasan_report+0x25/0x50 mm/kasan/common.c:641
 vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3275
 sscanf+0x6c/0x90 lib/vsprintf.c:3481
 smk_set_cipso+0x1ac/0x6a0 security/smack/smackfs.c:881
 __vfs_write+0xa7/0x710 fs/read_write.c:494
 __kernel_write+0x12f/0x340 fs/read_write.c:515
 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
 splice_direct_to_actor+0x482/0xb40 fs/splice.c:992
 do_splice_direct+0x201/0x340 fs/splice.c:1080
 do_sendfile+0x809/0xfd0 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1581 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x164/0x1a0 fs/read_write.c:1567
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c849
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f51bc217c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f51bc2186d4 RCX: 000000000045c849
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000003
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008d4 R14: 00000000004cb786 R15: 000000000076bf0c

Allocated by task 18470:
 save_stack mm/kasan/common.c:72 [inline]
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc+0x118/0x1c0 mm/kasan/common.c:515
 __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:494
 __kernel_write+0x12f/0x340 fs/read_write.c:515
 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
 splice_direct_to_actor+0x482/0xb40 fs/splice.c:992
 do_splice_direct+0x201/0x340 fs/splice.c:1080
 do_sendfile+0x809/0xfd0 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1581 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x164/0x1a0 fs/read_write.c:1567
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 55:
 save_stack mm/kasan/common.c:72 [inline]
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:337 [inline]
 __kasan_slab_free+0x12e/0x1e0 mm/kasan/common.c:476
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x220 mm/slab.c:3757
 security_sk_free+0x4d/0x90 security/security.c:2125
 sk_prot_free net/core/sock.c:1637 [inline]
 __sk_destruct+0x5f9/0x740 net/core/sock.c:1725
 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 ffff8880a6a7b480
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 4 bytes inside of
 32-byte region [ffff8880a6a7b480, ffff8880a6a7b4a0)
The buggy address belongs to the page:
page:ffffea00029a9ec0 refcount:1 mapcount:0 mapping:ffff8880aa4001c0 index:0xffff8880a6a7bfc1
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00029a5488 ffffea00028b0708 ffff8880aa4001c0
raw: ffff8880a6a7bfc1 ffff8880a6a7b000 000000010000003f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a6a7b380: 00 01 fc fc fc fc fc fc 00 00 00 00 fc fc fc fc
 ffff8880a6a7b400: 00 00 01 fc fc fc fc fc 00 00 01 fc fc fc fc fc
>ffff8880a6a7b480: 04 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc
                   ^
 ffff8880a6a7b500: 00 00 01 fc fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a6a7b580: 00 02 fc fc fc fc fc fc 05 fc fc fc fc fc fc fc
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