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BUG: KASAN: slab-out-of-bounds in vsscanf+0x2666/0x2ef0 lib/vsprintf.c:3275
Read of size 1 at addr ffff88809baf4682 by task syz-executor.2/11252

CPU: 1 PID: 11252 Comm: syz-executor.2 Not tainted 5.7.0-rc1-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 11252:
 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 7037:
 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
 __vunmap+0x973/0xa20 mm/vmalloc.c:2319
 copy_entries_to_user net/ipv4/netfilter/ip_tables.c:867 [inline]
 get_entries net/ipv4/netfilter/ip_tables.c:1024 [inline]
 do_ipt_get_ctl+0x77f/0x9b0 net/ipv4/netfilter/ip_tables.c:1700
 nf_sockopt net/netfilter/nf_sockopt.c:104 [inline]
 nf_getsockopt+0x2c1/0x2f0 net/netfilter/nf_sockopt.c:122
 ip_getsockopt+0x102/0x1e0 net/ipv4/ip_sockglue.c:1576
 __sys_getsockopt+0x255/0x2c0 net/socket.c:2177
 __do_sys_getsockopt net/socket.c:2192 [inline]
 __se_sys_getsockopt net/socket.c:2189 [inline]
 __x64_sys_getsockopt+0xb1/0xc0 net/socket.c:2189
 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 ffff88809baf4680
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 2 bytes inside of
 32-byte region [ffff88809baf4680, ffff88809baf46a0)
The buggy address belongs to the page:
page:ffffea00026ebd00 refcount:1 mapcount:0 mapping:0000000065c02f0b index:0xffff88809baf4fc1
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002912ec8 ffffea00024ec908 ffff8880aa4001c0
raw: ffff88809baf4fc1 ffff88809baf4000 0000000100000039 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809baf4580: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff88809baf4600: fb fb fb fb fc fc fc fc 00 01 fc fc fc fc fc fc
>ffff88809baf4680: 02 fc fc fc fc fc fc fc 00 01 fc fc fc fc fc fc
                   ^
 ffff88809baf4700: 00 00 01 fc fc fc fc fc 00 00 01 fc fc fc fc fc
 ffff88809baf4780: fb fb fb fb fc fc fc fc 00 00 00 fc fc fc fc fc
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