BUG: KASAN: stack-out-of-bounds in xfrm_state_find+0x303d/0x3170 net/xfrm/xfrm_state.c:1051
Read of size 4 at addr ffff880039506898 by task syzkaller346209/3047

CPU: 1 PID: 3047 Comm: syzkaller346209 Not tainted 4.13.0-rc5-next-20170817+ #5
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 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+0x24e/0x340 mm/kasan/report.c:409
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
 xfrm_state_find+0x303d/0x3170 net/xfrm/xfrm_state.c:1051
 xfrm_tmpl_resolve_one net/xfrm/xfrm_policy.c:1388 [inline]
 xfrm_tmpl_resolve+0x309/0xc00 net/xfrm/xfrm_policy.c:1432
 xfrm_resolve_and_create_bundle+0x186/0x24a0 net/xfrm/xfrm_policy.c:1830
 xfrm_lookup+0xefb/0x2540 net/xfrm/xfrm_policy.c:2141
 xfrm_lookup_route+0x39/0x1a0 net/xfrm/xfrm_policy.c:2260
 ip_route_output_flow+0x7c/0xa0 net/ipv4/route.c:2549
 inet_csk_route_req+0x5d8/0x990 net/ipv4/inet_connection_sock.c:550
 tcp_v4_send_synack+0x1e4/0x270 net/ipv4/tcp_ipv4.c:870
 tcp_rtx_synack+0x119/0x2e0 net/ipv4/tcp_output.c:3714
 inet_rtx_syn_ack+0x64/0xd0 net/ipv4/inet_connection_sock.c:634
 tcp_check_req+0xae3/0x1620 net/ipv4/tcp_minisocks.c:612
 tcp_v4_rcv+0x1e67/0x2e10 net/ipv4/tcp_ipv4.c:1672
 ip_local_deliver_finish+0x2e2/0xba0 net/ipv4/ip_input.c:216
 NF_HOOK include/linux/netfilter.h:248 [inline]
 ip_local_deliver+0x1ce/0x6d0 net/ipv4/ip_input.c:257
 dst_input include/net/dst.h:477 [inline]
 ip_rcv_finish+0x8db/0x19c0 net/ipv4/ip_input.c:397
 NF_HOOK include/linux/netfilter.h:248 [inline]
 ip_rcv+0xc3f/0x17d0 net/ipv4/ip_input.c:488
 __netif_receive_skb_core+0x19af/0x33d0 net/core/dev.c:4418
 __netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4456
 netif_receive_skb_internal+0x10b/0x5e0 net/core/dev.c:4527
 netif_receive_skb+0xae/0x390 net/core/dev.c:4551
 tun_rx_batched.isra.43+0x5e7/0x860 drivers/net/tun.c:1218
 tun_get_user+0x11dd/0x2150 drivers/net/tun.c:1539
 tun_chr_write_iter+0xd8/0x190 drivers/net/tun.c:1565
 call_write_iter include/linux/fs.h:1743 [inline]
 new_sync_write fs/read_write.c:457 [inline]
 __vfs_write+0x684/0x970 fs/read_write.c:470
 vfs_write+0x189/0x510 fs/read_write.c:518
 SYSC_write fs/read_write.c:565 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:557
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x405f81
RSP: 002b:00007f24f8731d80 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000405f81
RDX: 0000000000000036 RSI: 0000000020002000 RDI: 0000000000000003
RBP: 00007ffc25d22b00 R08: 0000000000000013 R09: 00007f24f8732700
R10: 00007f24f87329d0 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f24f87329c0 R15: 00007f24f8732700

The buggy address belongs to the page:
page:ffffea0000e54180 count:0 mapcount:0 mapping:          (null) index:0xffff880039506880
flags: 0x100000000000000()
raw: 0100000000000000 0000000000000000 ffff880039506880 00000000ffffffff
raw: dead000000000100 dead000000000200 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff880039506780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff880039506800: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00
>ffff880039506880: 00 00 00 f2 f3 f3 f3 f3 00 00 00 00 00 00 00 f1
                            ^
 ffff880039506900: f1 f1 f1 00 00 00 00 00 00 00 00 00 00 f2 f2 f3
 ffff880039506980: f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00
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