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BUG: KASAN: stack-out-of-bounds in strnlen+0xc1/0xd0 lib/string.c:498
Read of size 1 at addr ffff8800ae88fc14 by task syz-executor0/16952

CPU: 1 PID: 16952 Comm: syz-executor0 Not tainted 4.4.136-gfb7e319 #57
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 bbf74dd9ddf59c5c ffff8800ae88f680 ffffffff81e0edad
 ffffea0002ba23c0 ffff8800ae88fc14 0000000000000000 ffff8800ae88fc14
 ffff8800ae88fbe0 ffff8800ae88f6b8 ffffffff815159b6 ffff8800ae88fc14
Call Trace:
 [<ffffffff81e0edad>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e0edad>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff815159b6>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff81515cd5>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff81515cd5>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814f9764>] __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:426
 [<ffffffff81e2a8b1>] strnlen+0xc1/0xd0 lib/string.c:498
 [<ffffffff81e3299c>] string.isra.4+0x4c/0x250 lib/vsprintf.c:518
 [<ffffffff81e37b52>] vsnprintf+0x402/0x18e0 lib/vsprintf.c:1907
 [<ffffffff81e3905d>] vscnprintf+0x2d/0x60 lib/vsprintf.c:2010
 [<ffffffff8125d0df>] vprintk_emit+0xdf/0x840 kernel/printk/printk.c:1729
 [<ffffffff8125d868>] vprintk+0x28/0x30 kernel/printk/printk.c:1843
 [<ffffffff8125d88d>] vprintk_default+0x1d/0x30 kernel/printk/printk.c:1844
 [<ffffffff81415328>] printk+0xaf/0xd7 kernel/printk/printk.c:1922
 [<ffffffff8389e374>] do_ip_vs_set_ctl.cold.37+0x32/0x37 net/netfilter/ipvs/ip_vs_ctl.c:2394
 [<ffffffff830c6ded>] compat_nf_sockopt net/netfilter/nf_sockopt.c:145 [inline]
 [<ffffffff830c6ded>] compat_nf_setsockopt+0x10d/0x130 net/netfilter/nf_sockopt.c:155
 [<ffffffff83226ac7>] compat_ip_setsockopt+0xa7/0xe0 net/ipv4/ip_sockglue.c:1253
 [<ffffffff832cbcda>] compat_udp_setsockopt+0x4a/0x90 net/ipv4/udp.c:2172
 [<ffffffff83483ab4>] compat_ipv6_setsockopt+0xb4/0x1d0 net/ipv6/ipv6_sockglue.c:923
 [<ffffffff8322fd17>] inet_csk_compat_setsockopt+0x97/0x120 net/ipv4/inet_connection_sock.c:914
 [<ffffffff832445bd>] compat_tcp_setsockopt+0x3d/0x70 net/ipv4/tcp.c:2654
 [<ffffffff82f24984>] compat_sock_common_setsockopt+0xb4/0x150 net/core/sock.c:2670
 [<ffffffff8300b76c>] C_SYSC_setsockopt net/compat.c:385 [inline]
 [<ffffffff8300b76c>] compat_SyS_setsockopt+0x14c/0x2a0 net/compat.c:368
 [<ffffffff81006d96>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
 [<ffffffff81006d96>] do_fast_syscall_32+0x326/0x8b0 arch/x86/entry/common.c:459
 [<ffffffff838c416a>] sysenter_flags_fixed+0xd/0x17

The buggy address belongs to the page:
page:ffffea0002ba23c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8800ae88fb00: f2 f2 00 00 00 00 00 04 f2 f2 f2 f2 f2 f2 00 00
 ffff8800ae88fb80: 00 00 00 00 00 00 f2 f2 f2 f2 00 00 00 00 00 00
>ffff8800ae88fc00: 00 00 04 f2 f2 f2 00 00 00 00 00 00 00 00 00 00
                         ^
 ffff8800ae88fc80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8800ae88fd00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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