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BUG: KASAN: stack-out-of-bounds in memcmp+0x126/0x160 lib/string.c:768
Read of size 1 at addr ffff8801db707718 by task syz-executor3/9722

CPU: 1 PID: 9722 Comm: syz-executor3 Not tainted 4.9.131+ #50
 ffff8801db7072f8 ffffffff81b37029 ffffea00076dc1c0 ffff8801db707718
 0000000000000000 ffff8801db707718 ffff8801db707700 ffff8801db707330
 ffffffff81500aed ffff8801db707718 0000000000000001 0000000000000000
Call Trace:
 <IRQ> [  181.421369]  [<ffffffff81b37029>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [  181.421369]  [<ffffffff81b37029>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81500aed>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff81500ef7>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff81500ef7>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff814f30a4>] __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 [<ffffffff81b53b26>] memcmp+0x126/0x160 lib/string.c:768
 [<ffffffff8262c7a0>] addr_match include/net/xfrm.h:833 [inline]
 [<ffffffff8262c7a0>] __xfrm6_selector_match net/xfrm/xfrm_policy.c:87 [inline]
 [<ffffffff8262c7a0>] xfrm_selector_match+0x6a0/0xe40 net/xfrm/xfrm_policy.c:101
 [<ffffffff82631753>] xfrm_policy_match net/xfrm/xfrm_policy.c:1105 [inline]
 [<ffffffff82631753>] xfrm_policy_lookup_bytype.constprop.16+0xde3/0x1250 net/xfrm/xfrm_policy.c:1158
 [<ffffffff82631c14>] __xfrm_policy_lookup net/xfrm/xfrm_policy.c:1193 [inline]
 [<ffffffff82631c14>] xfrm_policy_lookup+0x54/0xb0 net/xfrm/xfrm_policy.c:1223
 [<ffffffff8235ba0b>] flow_cache_lookup+0x9db/0x1090 net/core/flow.c:273
 [<ffffffff8262fbbc>] __xfrm_policy_check+0x9ac/0x1760 net/xfrm/xfrm_policy.c:2512
 [<ffffffff826ff874>] __xfrm_policy_check2 include/net/xfrm.h:1063 [inline]
 [<ffffffff826ff874>] xfrm_policy_check include/net/xfrm.h:1072 [inline]
 [<ffffffff826ff874>] xfrm6_policy_check include/net/xfrm.h:1082 [inline]
 [<ffffffff826ff874>] rawv6_rcv+0x5c4/0xff0 net/ipv6/raw.c:419
 [<ffffffff8270060f>] ipv6_raw_deliver net/ipv6/raw.c:219 [inline]
 [<ffffffff8270060f>] raw6_local_deliver+0x36f/0x850 net/ipv6/raw.c:235
 [<ffffffff82691311>] ip6_input_finish+0x441/0x1560 net/ipv6/ip6_input.c:241
 [<ffffffff826925f1>] NF_HOOK_THRESH include/linux/netfilter.h:232 [inline]
 [<ffffffff826925f1>] NF_HOOK include/linux/netfilter.h:255 [inline]
 [<ffffffff826925f1>] ip6_input+0x1c1/0x350 net/ipv6/ip6_input.c:322
 [<ffffffff826909a5>] dst_input include/net/dst.h:513 [inline]
 [<ffffffff826909a5>] ip6_rcv_finish+0x155/0x680 net/ipv6/ip6_input.c:69
 [<ffffffff826937d7>] NF_HOOK_THRESH include/linux/netfilter.h:232 [inline]
 [<ffffffff826937d7>] NF_HOOK include/linux/netfilter.h:255 [inline]
 [<ffffffff826937d7>] ipv6_rcv+0x1057/0x1e60 net/ipv6/ip6_input.c:203
 [<ffffffff822ecb55>] __netif_receive_skb_core+0x12b5/0x2960 net/core/dev.c:4267
 [<ffffffff822f553b>] __netif_receive_skb+0x5b/0x1c0 net/core/dev.c:4305
 [<ffffffff822fd270>] process_backlog+0x1f0/0x650 net/core/dev.c:4926
 [<ffffffff822fc624>] napi_poll net/core/dev.c:5227 [inline]
 [<ffffffff822fc624>] net_rx_action+0x3a4/0xe00 net/core/dev.c:5292
 [<ffffffff82808ac0>] __do_softirq+0x210/0x940 kernel/softirq.c:288
 [<ffffffff8280469c>] do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:843
 <EOI> [  181.784366]  [<ffffffff810ef902>] do_softirq.part.1+0x62/0x70 kernel/softirq.c:332
 [<ffffffff810ef9d8>] do_softirq arch/x86/include/asm/preempt.h:22 [inline]
 [<ffffffff810ef9d8>] __local_bh_enable_ip+0xc8/0xd0 kernel/softirq.c:185
 [<ffffffff8267cb35>] local_bh_enable include/linux/bottom_half.h:31 [inline]
 [<ffffffff8267cb35>] rcu_read_unlock_bh include/linux/rcupdate.h:971 [inline]
 [<ffffffff8267cb35>] ip6_finish_output2+0xb55/0x1d10 net/ipv6/ip6_output.c:120
 [<ffffffff8268d634>] ip6_finish_output+0x334/0x980 net/ipv6/ip6_output.c:145
 [<ffffffff8268de6a>] NF_HOOK_COND include/linux/netfilter.h:246 [inline]
 [<ffffffff8268de6a>] ip6_output+0x1ea/0x6d0 net/ipv6/ip6_output.c:162
 [<ffffffff827a8ddb>] dst_output include/net/dst.h:507 [inline]
 [<ffffffff827a8ddb>] ip6_local_out+0x9b/0x180 net/ipv6/output_core.c:176
 [<ffffffff82690051>] ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1751
 [<ffffffff826903a3>] ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1771
 [<ffffffff826fe116>] rawv6_push_pending_frames net/ipv6/raw.c:611 [inline]
 [<ffffffff826fe116>] rawv6_sendmsg+0x1f36/0x2810 net/ipv6/raw.c:927
 [<ffffffff825833a3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:770
 [<ffffffff8228deab>] sock_sendmsg_nosec net/socket.c:648 [inline]
 [<ffffffff8228deab>] sock_sendmsg+0xbb/0x110 net/socket.c:658
 [<ffffffff8228e123>] sock_write_iter+0x223/0x3b0 net/socket.c:856
 [<ffffffff81508477>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff81508477>] __vfs_write+0x3d7/0x580 fs/read_write.c:509
 [<ffffffff8150acc7>] vfs_write+0x187/0x520 fs/read_write.c:557
 [<ffffffff8150eaf9>] SYSC_write fs/read_write.c:604 [inline]
 [<ffffffff8150eaf9>] SyS_write+0xd9/0x1c0 fs/read_write.c:596
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff828037d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the page:
page:ffffea00076dc1c0 count:1 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000400(reserved)
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801db707600: 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00
 ffff8801db707680: 00 00 00 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00
>ffff8801db707700: 00 00 00 f2 f2 00 00 00 00 00 00 00 00 00 00 00
                            ^
 ffff8801db707780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801db707800: 00 00 00 00 00 f1 f1 f1 f1 00 f2 f2 f2 00 00 00
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