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BUG: KASAN: stack-out-of-bounds in xfrm_state_find+0x305b/0x3190 net/xfrm/xfrm_state.c:1051
Read of size 4 at addr ffff8801c835e7a8 by task syz-executor2/9854

CPU: 0 PID: 9854 Comm: syz-executor2 Not tainted 4.14.0-rc3+ #75
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
 xfrm_state_find+0x305b/0x3190 net/xfrm/xfrm_state.c:1051
sctp: [Deprecated]: syz-executor6 (pid 9884) Use of struct sctp_assoc_value in delayed_ack socket option.
Use struct sctp_sack_info instead
sctp: [Deprecated]: syz-executor6 (pid 9887) Use of struct sctp_assoc_value in delayed_ack socket option.
Use struct sctp_sack_info instead
 xfrm_tmpl_resolve_one net/xfrm/xfrm_policy.c:1388 [inline]
 xfrm_tmpl_resolve+0x2fb/0xbd0 net/xfrm/xfrm_policy.c:1432
 xfrm_resolve_and_create_bundle+0x186/0x24b0 net/xfrm/xfrm_policy.c:1830
 xfrm_lookup+0xf0a/0x2540 net/xfrm/xfrm_policy.c:2141
 xfrm_lookup_route+0x39/0x1a0 net/xfrm/xfrm_policy.c:2259
 ip_route_output_flow+0x7c/0xa0 net/ipv4/route.c:2555
 inet_csk_route_req+0x5d8/0x990 net/ipv4/inet_connection_sock.c:552
 tcp_v4_send_synack+0x1e4/0x270 net/ipv4/tcp_ipv4.c:870
 tcp_rtx_synack+0x119/0x2e0 net/ipv4/tcp_output.c:3726
 inet_rtx_syn_ack+0x64/0xd0 net/ipv4/inet_connection_sock.c:636
 tcp_check_req+0xae3/0x1620 net/ipv4/tcp_minisocks.c:615
 tcp_v4_rcv+0x17f6/0x2f80 net/ipv4/tcp_ipv4.c:1675
 ip_local_deliver_finish+0x2e2/0xba0 net/ipv4/ip_input.c:216
 NF_HOOK include/linux/netfilter.h:249 [inline]
 ip_local_deliver+0x1ce/0x6e0 net/ipv4/ip_input.c:257
 dst_input include/net/dst.h:464 [inline]
 ip_rcv_finish+0x887/0x19a0 net/ipv4/ip_input.c:397
 NF_HOOK include/linux/netfilter.h:249 [inline]
 ip_rcv+0xc3f/0x1820 net/ipv4/ip_input.c:493
 __netif_receive_skb_core+0x1a3e/0x34b0 net/core/dev.c:4476
 __netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4514
 netif_receive_skb_internal+0x10b/0x670 net/core/dev.c:4587
 netif_receive_skb+0xae/0x390 net/core/dev.c:4611
 tun_rx_batched.isra.50+0x5ed/0x860 drivers/net/tun.c:1372
 tun_get_user+0x249c/0x36d0 drivers/net/tun.c:1766
 tun_chr_write_iter+0xbf/0x160 drivers/net/tun.c:1792
 call_write_iter include/linux/fs.h:1770 [inline]
 new_sync_write fs/read_write.c:468 [inline]
 __vfs_write+0x68a/0x970 fs/read_write.c:481
 vfs_write+0x18f/0x510 fs/read_write.c:543
 SYSC_write fs/read_write.c:588 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:580
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x40c341
RSP: 002b:00007ff3e97d4c10 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000718000 RCX: 000000000040c341
RDX: 0000000000000036 RSI: 00000000204ecfca RDI: 0000000000000015
RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000f4240 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000a6f7ef R14: 00007ff3e97d59c0 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea000720d780 count:0 mapcount:0 mapping:          (null) index:0xffff8801c835e9c0
flags: 0x200000000000000()
raw: 0200000000000000 0000000000000000 ffff8801c835e9c0 00000000ffffffff
raw: 0000000000000000 dead000000000200 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c835e680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c835e700: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00
>ffff8801c835e780: 00 00 00 00 00 f2 f3 f3 f3 f3 00 00 00 00 00 00
                                  ^
 ffff8801c835e800: 00 f1 f1 f1 f1 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c835e880: f2 f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00
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