syzbot

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 27897 Comm: syz-executor1 Not tainted 4.9.117-g8b21e85 #71
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801a3ab4800 task.stack: ffff8801c7af8000
RIP: 0010:[<ffffffff83504b43>]  [<ffffffff83504b43>] xfrm_policy_ok net/xfrm/xfrm_policy.c:2410 [inline]
RIP: 0010:[<ffffffff83504b43>]  [<ffffffff83504b43>] __xfrm_policy_check+0xc93/0x1b20 net/xfrm/xfrm_policy.c:2586
RSP: 0018:ffff8801db307580  EFLAGS: 00010202
RAX: 000000000000000a RBX: 0000000000000020 RCX: ffff8801a3ab4800
RDX: 0000000000000002 RSI: ffffffff83504b12 RDI: 0000000000000052
RBP: ffff8801db3077c8 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: ffff8801db3076c0 R14: dffffc0000000000 R15: 0000000000000000
FS:  00007f78c2613700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001d7993000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff83503fef ffff8801db307620 ffff8801db3076b8 0000000200000001
 ffff8801db307628 ffff8801c7931a68 0000000200020002 ffff8801db3076c8
 ffff8801bbd69680 ffff880100000002 1ffff1003b660ec0 ffff8801db307720
Call Trace:
 [<ffffffff833ff33d>] __xfrm_policy_check2 include/net/xfrm.h:1063 [inline]
 [<ffffffff833ff33d>] xfrm_policy_check include/net/xfrm.h:1072 [inline]
 [<ffffffff833ff33d>] xfrm4_policy_check include/net/xfrm.h:1077 [inline]
 [<ffffffff833ff33d>] udp_queue_rcv_skb+0xa2d/0x1770 net/ipv4/udp.c:1512
 [<ffffffff83400c7b>] __udp4_lib_rcv+0xbfb/0x2b10 net/ipv4/udp.c:1780
 [<ffffffff83403c21>] udp_rcv+0x21/0x30 net/ipv4/udp.c:1972
 [<ffffffff83325037>] ip_local_deliver_finish+0x257/0xa60 net/ipv4/ip_input.c:216
 [<ffffffff83327a29>] NF_HOOK_THRESH include/linux/netfilter.h:232 [inline]
 [<ffffffff83327a29>] NF_HOOK include/linux/netfilter.h:255 [inline]
 [<ffffffff83327a29>] ip_local_deliver+0x389/0x4d0 net/ipv4/ip_input.c:257
 [<ffffffff83325f16>] dst_input include/net/dst.h:513 [inline]
 [<ffffffff83325f16>] ip_rcv_finish+0x6d6/0x1920 net/ipv4/ip_input.c:396
 [<ffffffff8332867b>] NF_HOOK_THRESH include/linux/netfilter.h:232 [inline]
 [<ffffffff8332867b>] NF_HOOK include/linux/netfilter.h:255 [inline]
 [<ffffffff8332867b>] ip_rcv+0xb0b/0x1370 net/ipv4/ip_input.c:487
 [<ffffffff8307e110>] __netif_receive_skb_core+0x12a0/0x2a20 net/core/dev.c:4267
 [<ffffffff8307f8eb>] __netif_receive_skb+0x5b/0x1c0 net/core/dev.c:4305
 [<ffffffff8307fc56>] process_backlog+0x206/0x6a0 net/core/dev.c:4926
 [<ffffffff83085cb4>] napi_poll net/core/dev.c:5227 [inline]
 [<ffffffff83085cb4>] net_rx_action+0x3c4/0xde0 net/core/dev.c:5292
 [<ffffffff83a037fb>] __do_softirq+0x20b/0x937 kernel/softirq.c:284
 [<ffffffff839fdc1c>] do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:843
 <EOI> [  383.053772]  [<ffffffff81149859>] do_softirq.part.14+0x99/0xb0 kernel/softirq.c:328
 [<ffffffff8114b059>] do_softirq+0x19/0x20 kernel/softirq.c:331
 [<ffffffff8308314d>] netif_rx_ni+0xbd/0x310 net/core/dev.c:3897
 [<ffffffff82816d91>] tun_get_user+0xe21/0x2210 drivers/net/tun.c:1330
netlink: 268 bytes leftover after parsing attributes in process `syz-executor4'.
netlink: 268 bytes leftover after parsing attributes in process `syz-executor4'.
 [<ffffffff82818395>] tun_chr_write_iter+0xd5/0x190 drivers/net/tun.c:1353
 [<ffffffff815710b4>] do_iter_readv_writev+0x3d4/0x4b0 fs/read_write.c:695
 [<ffffffff815734f6>] do_readv_writev+0x2f6/0x7a0 fs/read_write.c:871
 [<ffffffff81573f87>] vfs_writev+0x87/0xc0 fs/read_write.c:910
 [<ffffffff815740a6>] do_writev+0xe6/0x260 fs/read_write.c:943
 [<ffffffff815773d7>] SYSC_writev fs/read_write.c:1016 [inline]
 [<ffffffff815773d7>] SyS_writev+0x27/0x30 fs/read_write.c:1013
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fcc13>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: ff 48 c1 e8 03 42 80 3c 30 00 0f 85 52 0c 00 00 48 8b 85 f0 fd ff ff 48 8b 18 48 8d 7b 32 48 89 f8 48 89 fa 48 c1 e8 03 83 e2 07 <42> 0f b6 04 30 38 d0 7f 08 84 c0 0f 85 bd 0c 00 00 0f b6 43 32 
RIP  [<ffffffff83504b43>] xfrm_policy_ok net/xfrm/xfrm_policy.c:2410 [inline]
RIP  [<ffffffff83504b43>] __xfrm_policy_check+0xc93/0x1b20 net/xfrm/xfrm_policy.c:2586
 RSP <ffff8801db307580>
---[ end trace 8bc1114cf311dba8 ]---