general protection fault in ip6_xmit (2)

[syzbot]

Hello,

syzbot hit the following crash on net-next commit
6bb46bc57c8e9ce947cc605e555b7204b44d2b10 (Fri Jan 26 16:00:23 2018 +0000)
Merge branch 'cxgb4-fix-dump-collection-when-firmware-crashed'

So far this crash happened 2 times on net-next.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

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kasan: CONFIG_KASAN_INLINE enabled
xt_CT: netfilter: NOTRACK target is deprecated, use CT instead or upgrade
iptables
xt_CT: You must specify a L4 protocol, and not use inversions on it.
xt_CT: You must specify a L4 protocol, and not use inversions on it.
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 12438 Comm: syz-executor5 Not tainted 4.15.0-rc9+ #212
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:ip6_xmit+0xc16/0x2260 net/ipv6/ip6_output.c:264
RSP: 0018:ffff8801c7a7f588 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff8801c08f8e80 RCX: ffffffff84beaeed
RDX: 000000001fff8b3f RSI: ffffc900018fc000 RDI: 00000000fffc59ff
RBP: ffff8801c7a7f7f8 R08: 1ffff1003811f101 R09: ffff8801c7a7f748
R10: ffff8801c7a7f588 R11: ffffed0038f4fef0 R12: 00000000fffc572f
R13: ffffed0038f4fee9 R14: 0000000000000040 R15: ffff8801d41bb324
FS: 00007f56ad8d3700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020e77000 CR3: 00000001bba1e006 CR4: 00000000001606e0
IPVS: set_ctl: invalid protocol: 13703 39.52.93.236:60696
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DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
IPVS: set_ctl: invalid protocol: 13703 39.52.93.236:60696
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Call Trace:
inet6_csk_xmit+0x2fc/0x580 net/ipv6/inet6_connection_sock.c:139
l2tp_xmit_core net/l2tp/l2tp_core.c:1096 [inline]
l2tp_xmit_skb+0x105f/0x1410 net/l2tp/l2tp_core.c:1191
pppol2tp_sendmsg+0x470/0x670 net/l2tp/l2tp_ppp.c:341
sock_sendmsg_nosec net/socket.c:630 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:640
___sys_sendmsg+0x767/0x8b0 net/socket.c:2046
__sys_sendmsg+0xe5/0x210 net/socket.c:2080
SYSC_sendmsg net/socket.c:2091 [inline]
SyS_sendmsg+0x2d/0x50 net/socket.c:2087
entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x453299
RSP: 002b:00007f56ad8d2c58 EFLAGS: 00000212 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000453299
RDX: 0000000000000081 RSI: 000000002037ffc8 RDI: 0000000000000014
RBP: 000000000000005c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006ef940
R13: 00000000ffffffff R14: 00007f56ad8d36d4 R15: 0000000000000000
Code: 4d 8b a4 24 18 01 00 00 4d 85 e4 74 67 e8 f3 84 b1 fc 49 8d bc 24 d0
02 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00
0f 85 5b 13 00 00 48 8b 95 e0 fd ff ff 48 b8 00 00
RIP: ip6_xmit+0xc16/0x2260 net/ipv6/ip6_output.c:264 RSP: ffff8801c7a7f588
---[ end trace 9d91ca16e8c43649 ]---
Kernel panic - not syncing: Fatal exception in interrupt
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[syzbot]

> #syz test:
> https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git

This crash does not have a reproducer. I cannot test it.

> master

> On 31 January 2018 at 12:39, syzbot

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.