general protection fault in rt_cache_valid

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: b71acb0e3721 Merge branch 'linus' of git://git.kernel.org/..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1582bc30c00000
kernel config: https://syzkaller.appspot.com/x/.config?x=b03c5892bb940c76
dashboard link: https://syzkaller.appspot.com/bug?extid=92dce31b571f5ac0d528
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [da...@davemloft.net kuz...@ms2.inr.ac.ru
linux-...@vger.kernel.org net...@vger.kernel.org yosh...@linux-ipv6.org
net...@vger.kernel.org]

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+92dce3...@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: 1 PID: 2230 Comm: syz-executor0 Not tainted 4.20.0+ #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:rt_cache_valid+0x85/0x250 net/ipv4/route.c:1510
Code: 04 25 28 00 00 00 48 89 45 d0 31 c0 e8 34 92 f1 fa 48 85 db 74 4a e8
2a 92 f1 fa 48 8d 7b 3a 4c 8d 75 d8 48 89 f8 48 c1 e8 03 <42> 0f b6 14 28
48 89 f8 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85
kobject: 'loop3' (000000002d125388): kobject_uevent_env
RSP: 0018:ffff88809b24e0a8 EFLAGS: 00010207
RAX: 0000000000000024 RBX: 00000000000000eb RCX: ffffc90005df9000
RDX: 00000000000016a8 RSI: ffffffff869013e6 RDI: 0000000000000125
RBP: ffff88809b24e130 R08: ffff88806586e0c0 R09: ffffed1015ce5b90
R10: ffffed1015ce5b8f R11: ffff8880ae72dc7b R12: 1ffff11013649c15
R13: dffffc0000000000 R14: ffff88809b24e108 R15: 0000000000000000
FS: 00007f9fa034d700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33722000 CR3: 000000008512a000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__mkroute_output net/ipv4/route.c:2260 [inline]
ip_route_output_key_hash_rcu+0x952/0x3470 net/ipv4/route.c:2492
kobject: 'loop3' (000000002d125388): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop5' (00000000a20c7830): kobject_uevent_env
ip_route_output_key_hash+0x25d/0x400 net/ipv4/route.c:2321
kobject: 'loop5' (00000000a20c7830): fill_kobj_path: path
= '/devices/virtual/block/loop5'
icmp_route_lookup.constprop.0+0x458/0x18e0 net/ipv4/icmp.c:489
kobject: 'loop2' (000000009de45ca1): kobject_uevent_env
icmp_send+0x12eb/0x1bc0 net/ipv4/icmp.c:714
kobject: 'loop2' (000000009de45ca1): fill_kobj_path: path
= '/devices/virtual/block/loop2'
ipv4_link_failure+0x2c/0x210 net/ipv4/route.c:1187
dst_link_failure include/net/dst.h:427 [inline]
vti_xmit net/ipv4/ip_vti.c:229 [inline]
vti_tunnel_xmit+0x85a/0x1730 net/ipv4/ip_vti.c:264
__netdev_start_xmit include/linux/netdevice.h:4382 [inline]
netdev_start_xmit include/linux/netdevice.h:4391 [inline]
xmit_one net/core/dev.c:3278 [inline]
dev_hard_start_xmit+0x261/0xc70 net/core/dev.c:3294
kobject: 'loop2' (000000009de45ca1): kobject_uevent_env
kobject: 'loop2' (000000009de45ca1): fill_kobj_path: path
= '/devices/virtual/block/loop2'
__dev_queue_xmit+0x2f8a/0x3a60 net/core/dev.c:3864
kobject: 'loop1' (00000000f4ea9cf1): kobject_uevent_env
kobject: 'loop1' (00000000f4ea9cf1): fill_kobj_path: path
= '/devices/virtual/block/loop1'
dev_queue_xmit+0x18/0x20 net/core/dev.c:3897
neigh_direct_output+0x16/0x20 net/core/neighbour.c:1511
kobject: 'loop1' (00000000f4ea9cf1): kobject_uevent_env
neigh_output include/net/neighbour.h:508 [inline]
ip_finish_output2+0xa35/0x1a00 net/ipv4/ip_output.c:229
kobject: 'loop1' (00000000f4ea9cf1): fill_kobj_path: path
= '/devices/virtual/block/loop1'
ip_finish_output+0x7e4/0xf60 net/ipv4/ip_output.c:317
NF_HOOK_COND include/linux/netfilter.h:278 [inline]
ip_output+0x226/0x880 net/ipv4/ip_output.c:405
dst_output include/net/dst.h:444 [inline]
ip_local_out+0xc4/0x1b0 net/ipv4/ip_output.c:124
ip_send_skb+0x42/0xf0 net/ipv4/ip_output.c:1465
udp_send_skb.isra.0+0x6b2/0x1160 net/ipv4/udp.c:891
udp_sendmsg+0x2902/0x3a40 net/ipv4/udp.c:1178
udpv6_sendmsg+0x1843/0x3550 net/ipv6/udp.c:1279
kobject: 'loop4' (000000007ece3fce): kobject_uevent_env
kobject: 'loop4' (000000007ece3fce): fill_kobj_path: path
= '/devices/virtual/block/loop4'
inet_sendmsg+0x1af/0x740 net/ipv4/af_inet.c:798
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg+0xdd/0x130 net/socket.c:631
___sys_sendmsg+0x409/0x910 net/socket.c:2116
__sys_sendmmsg+0x246/0x6f0 net/socket.c:2211
__do_sys_sendmmsg net/socket.c:2240 [inline]
__se_sys_sendmmsg net/socket.c:2237 [inline]
__x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2237
do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457ec9
Code: 6d b7 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 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f9fa034cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000457ec9
RDX: 00000000000004ff RSI: 00000000200092c0 RDI: 0000000000000004
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
kobject: 'loop4' (000000007ece3fce): kobject_uevent_env
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9fa034d6d4
R13: 00000000004c4ce5 R14: 00000000004d85d8 R15: 00000000ffffffff
Modules linked in:
---[ end trace bf211f6e476e0c45 ]---
RIP: 0010:rt_cache_valid+0x85/0x250 net/ipv4/route.c:1510
kobject: 'loop4' (000000007ece3fce): fill_kobj_path: path
= '/devices/virtual/block/loop4'
Code: 04 25 28 00 00 00 48 89 45 d0 31 c0 e8 34 92 f1 fa 48 85 db 74 4a e8
2a 92 f1 fa 48 8d 7b 3a 4c 8d 75 d8 48 89 f8 48 c1 e8 03 <42> 0f b6 14 28
48 89 f8 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85
RSP: 0018:ffff88809b24e0a8 EFLAGS: 00010207
RAX: 0000000000000024 RBX: 00000000000000eb RCX: ffffc90005df9000
RDX: 00000000000016a8 RSI: ffffffff869013e6 RDI: 0000000000000125
RBP: ffff88809b24e130 R08: ffff88806586e0c0 R09: ffffed1015ce5b90
kobject: 'loop5' (00000000a20c7830): kobject_uevent_env
R10: ffffed1015ce5b8f R11: ffff8880ae72dc7b R12: 1ffff11013649c15
R13: dffffc0000000000 R14: ffff88809b24e108 R15: 0000000000000000
FS: 00007f9fa034d700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
kobject: 'loop5' (00000000a20c7830): fill_kobj_path: path
= '/devices/virtual/block/loop5'
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33722000 CR3: 000000008512a000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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[Dmitry Vyukov]

#syz upstream

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