general protection fault in udpv6_queue_rcv_skb

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 62872f95 Merge 4.4.174 into android-4.4
git tree: android-4.4
console output: https://syzkaller.appspot.com/x/log.txt?x=1513536cc00000
kernel config: https://syzkaller.appspot.com/x/.config?x=47bc4dd423780c4a
dashboard link: https://syzkaller.appspot.com/bug?extid=3f393a3ddeabbb7b068c
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12169dd0c00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=174d5970c00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+3f393a...@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral
protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 2074 Comm: syz-executor668 Not tainted 4.4.174+ #4
task: ffff8800b71317c0 task.stack: ffff8801d41f0000
RIP: 0010:[<ffffffff8261569d>] [<ffffffff8261569d>] __xfrm_policy_check2
include/net/xfrm.h:1070 [inline]
RIP: 0010:[<ffffffff8261569d>] [<ffffffff8261569d>] xfrm_policy_check
include/net/xfrm.h:1076 [inline]
RIP: 0010:[<ffffffff8261569d>] [<ffffffff8261569d>] xfrm6_policy_check
include/net/xfrm.h:1086 [inline]
RIP: 0010:[<ffffffff8261569d>] [<ffffffff8261569d>]
udpv6_queue_rcv_skb+0x18d/0x14d0 net/ipv6/udp.c:634
RSP: 0018:ffff8801d41f79e8 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffffffff82615684 RDI: 0000000000000060
RBP: ffff8801d41f7a30 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8800b6430000
R13: ffff8800b7065780 R14: 0000000000000000 R15: ffff8800b70657d8
FS: 0000000002011880(0063) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000080 CR3: 00000000ba369000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
ffff8800b71317c0 ffff880000000001 ffff8800b6430088 ffff8800b6430088
ffff8800b6430000 ffff8800b7065780 dffffc0000000000 ffff8800b6430088
0000000000000000 ffff8801d41f7aa0 ffffffff821e5e40 ffff8800b6430430
Call Trace:
[<ffffffff821e5e40>] sk_backlog_rcv include/net/sock.h:875 [inline]
[<ffffffff821e5e40>] __release_sock net/core/sock.c:2024 [inline]
[<ffffffff821e5e40>] release_sock+0x170/0x500 net/core/sock.c:2477
[<ffffffff82612d88>] udpv6_sendmsg+0x8d8/0x24f0 net/ipv6/udp.c:1364
[<ffffffff824a8b42>] inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:755
[<ffffffff821d838e>] sock_sendmsg_nosec net/socket.c:638 [inline]
[<ffffffff821d838e>] sock_sendmsg+0xbe/0x110 net/socket.c:648
[<ffffffff821dc4f1>] SYSC_sendto net/socket.c:1678 [inline]
[<ffffffff821dc4f1>] SyS_sendto+0x201/0x340 net/socket.c:1646
[<ffffffff82718ba1>] entry_SYSCALL_64_fastpath+0x1e/0x9a
Code: 8b 75 58 41 f6 c6 01 0f 85 d9 07 00 00 e8 6c 3f cf fe 49 83 e6 fe 48
b8 00 00 00 00 00 fc ff df 49 8d 7e 60 48 89 fa 48 c1 ea 03 <0f> b6 04 02
84 c0 74 08 3c 01 0f 8e 8b 0e 00 00 41 f6 46 60 04
RIP [<ffffffff8261569d>] __xfrm_policy_check2 include/net/xfrm.h:1070
[inline]
RIP [<ffffffff8261569d>] xfrm_policy_check include/net/xfrm.h:1076 [inline]
RIP [<ffffffff8261569d>] xfrm6_policy_check include/net/xfrm.h:1086
[inline]
RIP [<ffffffff8261569d>] udpv6_queue_rcv_skb+0x18d/0x14d0
net/ipv6/udp.c:634
RSP <ffff8801d41f79e8>
---[ end trace 53711117613fb82c ]---


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