general protection fault in xfrm_policy_lookup_bytype

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 90cadbbf341d Merge git://git.kernel.org/pub/scm/linux/kern..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1018bf67400000
kernel config: https://syzkaller.appspot.com/x/.config?x=f9a32c9a4aef9af7
dashboard link: https://syzkaller.appspot.com/bug?extid=80f2c1182f5bf39e5208
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+80f2c1...@syzkaller.appspotmail.com

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
CPU: 0 PID: 25894 Comm: syz-executor0 Not tainted 4.20.0-rc7+ #361
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:__xfrm_policy_eval_candidates net/xfrm/xfrm_policy.c:2019 [inline]
RIP: 0010:xfrm_policy_eval_candidates net/xfrm/xfrm_policy.c:2053 [inline]
RIP: 0010:xfrm_policy_lookup_bytype+0xc1b/0xe70 net/xfrm/xfrm_policy.c:2113
Code: 7f fe ff ff e8 f6 59 c1 fa 4d 89 e6 49 83 ee 08 0f 84 6d fe ff ff e8
e4 59 c1 fa 49 8d bc 24 ac 00 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 14 28
48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85
kobject: 'loop1' (0000000000151e1f): kobject_uevent_env
RSP: 0018:ffff8880ae606ba8 EFLAGS: 00010203
RAX: 0000000020000015 RBX: 0000000000000000 RCX: ffffffff86bd011c
RDX: 0000000000000100 RSI: ffffffff86bd013c RDI: 00000001000000ac
RBP: ffff8880ae606e60 R08: ffff88809e8c4400 R09: 0000000000000000
kobject: 'loop1' (0000000000151e1f): fill_kobj_path: path
= '/devices/virtual/block/loop1'
R10: 0000000000000000 R11: ffff88809e8c4400 R12: 0000000100000000
R13: dffffc0000000000 R14: 00000000fffffff8 R15: 00000000ffffffff
FS: 00007f6c92e5d700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004cd730 CR3: 00000000a5cf0000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
xfrm_policy_lookup+0x7e/0x80 net/xfrm/xfrm_policy.c:2145
__xfrm_policy_check+0x14f0/0x2c40 net/xfrm/xfrm_policy.c:3354
__xfrm_policy_check2 include/net/xfrm.h:1170 [inline]
xfrm_policy_check include/net/xfrm.h:1175 [inline]
xfrm6_policy_check include/net/xfrm.h:1185 [inline]
ip6_protocol_deliver_rcu+0x8e9/0x1940 net/ipv6/ip6_input.c:391
ip6_input_finish+0x84/0x170 net/ipv6/ip6_input.c:434
NF_HOOK include/linux/netfilter.h:289 [inline]
ip6_input+0xe9/0x600 net/ipv6/ip6_input.c:443
ip6_mc_input+0x514/0x11c0 net/ipv6/ip6_input.c:537
dst_input include/net/dst.h:450 [inline]
ip6_rcv_finish+0x17a/0x330 net/ipv6/ip6_input.c:76
NF_HOOK include/linux/netfilter.h:289 [inline]
ipv6_rcv+0x115/0x640 net/ipv6/ip6_input.c:272
__netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4973
__netif_receive_skb+0x2c/0x1e0 net/core/dev.c:5083
process_backlog+0x217/0x760 net/core/dev.c:5923
napi_poll net/core/dev.c:6346 [inline]
net_rx_action+0x7c5/0x1950 net/core/dev.c:6412
__do_softirq+0x30c/0xb2e kernel/softirq.c:292
do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1027
</IRQ>
do_softirq.part.13+0x126/0x160 kernel/softirq.c:337
do_softirq+0x19/0x20 kernel/softirq.c:340
netif_rx_ni+0x521/0x870 net/core/dev.c:4569
dev_loopback_xmit+0x287/0x8c0 net/core/dev.c:3576
NF_HOOK include/linux/netfilter.h:289 [inline]
ip6_finish_output2+0x193a/0x2930 net/ipv6/ip6_output.c:84
ip6_finish_output+0x583/0xc50 net/ipv6/ip6_output.c:154
NF_HOOK_COND include/linux/netfilter.h:278 [inline]
ip6_output+0x232/0x9d0 net/ipv6/ip6_output.c:171
dst_output include/net/dst.h:444 [inline]
ip6_local_out+0xc5/0x1b0 net/ipv6/output_core.c:176
ip6_send_skb+0xbc/0x340 net/ipv6/ip6_output.c:1727
ip6_push_pending_frames+0xc5/0xf0 net/ipv6/ip6_output.c:1747
l2tp_ip6_push_pending_frames net/l2tp/l2tp_ip6.c:482 [inline]
l2tp_ip6_sendmsg+0x1d04/0x2190 net/l2tp/l2tp_ip6.c:643
inet_sendmsg+0x1a1/0x690 net/ipv4/af_inet.c:798
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:631
___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
__sys_sendmsg+0x11d/0x280 net/socket.c:2154
__do_sys_sendmsg net/socket.c:2163 [inline]
__se_sys_sendmsg net/socket.c:2161 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4579b9
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f6c92e5cc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004579b9
RDX: 0000000000000000 RSI: 00000000200014c0 RDI: 0000000000000004
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6c92e5d6d4
R13: 00000000004c4d3b R14: 00000000004d84a8 R15: 00000000ffffffff
Modules linked in:
---[ end trace 5178ef7fa63f0d3d ]---
RIP: 0010:__xfrm_policy_eval_candidates net/xfrm/xfrm_policy.c:2019 [inline]
RIP: 0010:xfrm_policy_eval_candidates net/xfrm/xfrm_policy.c:2053 [inline]
RIP: 0010:xfrm_policy_lookup_bytype+0xc1b/0xe70 net/xfrm/xfrm_policy.c:2113
Code: 7f fe ff ff e8 f6 59 c1 fa 4d 89 e6 49 83 ee 08 0f 84 6d fe ff ff e8
e4 59 c1 fa 49 8d bc 24 ac 00 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 14 28
48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85
RSP: 0018:ffff8880ae606ba8 EFLAGS: 00010203
RAX: 0000000020000015 RBX: 0000000000000000 RCX: ffffffff86bd011c
RDX: 0000000000000100 RSI: ffffffff86bd013c RDI: 00000001000000ac
RBP: ffff8880ae606e60 R08: ffff88809e8c4400 R09: 0000000000000000
R10: 0000000000000000 R11: ffff88809e8c4400 R12: 0000000100000000
R13: dffffc0000000000 R14: 00000000fffffff8 R15: 00000000ffffffff
FS: 00007f6c92e5d700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004cd730 CR3: 00000000a5cf0000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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[Florian Westphal]

syzbot <syzbot+80f2c1...@syzkaller.appspotmail.com> wrote:
> HEAD commit: 90cadbbf341d Merge git://git.kernel.org/pub/scm/linux/kern..
> git tree: net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1018bf67400000
> kernel config: https://syzkaller.appspot.com/x/.config?x=f9a32c9a4aef9af7
> dashboard link: https://syzkaller.appspot.com/bug?extid=80f2c1182f5bf39e5208

Possibly resolved by xfrm policy fixup series whose topmost commit is

#syz fix: xfrm: policy: fix infinite loop when merging src-nodes