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BUG: KASAN: slab-out-of-bounds in vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3275
Read of size 1 at addr ffff8880a0a2c8ca by task syz-executor.3/8638

CPU: 0 PID: 8638 Comm: syz-executor.3 Not tainted 5.7.0-rc5-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 8638:
 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
 splice_direct_to_actor+0x482/0xb40 fs/splice.c:992
 do_splice_direct+0x201/0x340 fs/splice.c:1080
 do_sendfile+0x809/0xfe0 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1582 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0x164/0x1a0 fs/read_write.c:1568
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8880a0a2c8c0
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 10 bytes inside of
 32-byte region [ffff8880a0a2c8c0, ffff8880a0a2c8e0)
The buggy address belongs to the page:
page:ffffea0002828b00 refcount:1 mapcount:0 mapping:00000000363aface index:0xffff8880a0a2cfc1
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002409148 ffffea00013c7fc8 ffff8880aa4001c0
raw: ffff8880a0a2cfc1 ffff8880a0a2c000 000000010000003f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a0a2c780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a0a2c800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a0a2c880: 00 02 fc fc fc fc fc fc 00 02 fc fc fc fc fc fc
                                              ^
 ffff8880a0a2c900: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a0a2c980: 00 00 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
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