BUG: unable to handle kernel paging request in dst_dev_put

[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=132246e3400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b03c5892bb940c76
dashboard link: https://syzkaller.appspot.com/bug?extid=a43d8d4e7e8a7a9e149e
compiler:       gcc (GCC) 9.0.0 20181231 (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+a43d8d4e7e8a7a9e149e@xxxxxxxxxxxxxxxxxxxxxxxxx

netlink: 'syz-executor2': attribute type 3 has an invalid length.
BUG: unable to handle kernel paging request at ffffed1bc3404006
#PF error: [normal kernel read fault]
PGD 21fff0067 P4D 21fff0067 PUD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 8160 Comm: syz-executor3 Not tainted 4.20.0+ #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:dst_dev_put+0xa0/0x290 net/core/dst.c:171
Code: fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 e4 01 00 00 48 b8 00 00 00 00  
00 fc ff df 4c 8b 6b 08 49 8d 7d 38 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f  
85 b7 01 00 00 4d 8b 75 38 4d 89 e5 4d 85 f6 74 33
RSP: 0018:ffff88808dc47520 EFLAGS: 00010a07
RAX: dffffc0000000000 RBX: ffff8880a4b36806 RCX: ffffc9000c042000
RDX: 1ffff11bc3404006 RSI: ffffffff8625e0d3 RDI: ffff88de1a020037
RBP: ffff88808dc47540 R08: 1ffffd1ffff8e344 R09: fffff91ffff8e345
R10: fffff91ffff8e344 R11: ffffe8ffffc71a27 R12: ffff8a391080ffff
R13: ffff88de1a01ffff R14: 1ffff11011b88eb5 R15: ffff88808dc475f8
FS:  00007f83b5508700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed1bc3404006 CR3: 0000000065801000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 rt_cache_route+0x377/0x460 net/ipv4/route.c:1438
 rt_set_nexthop.constprop.0+0x420/0x1400 net/ipv4/route.c:1538
 __mkroute_output net/ipv4/route.c:2293 [inline]
 ip_route_output_key_hash_rcu+0xb07/0x3470 net/ipv4/route.c:2492
 ip_route_output_key_hash+0x25d/0x400 net/ipv4/route.c:2321
 __ip_route_output_key include/net/route.h:124 [inline]
 ip_route_output_flow+0x28/0xc0 net/ipv4/route.c:2576
 ip_route_connect include/net/route.h:309 [inline]
 tcp_v4_connect+0x8a3/0x1da0 net/ipv4/tcp_ipv4.c:233
 __inet_stream_connect+0x9a3/0x11b0 net/ipv4/af_inet.c:655
 inet_stream_connect+0x58/0xa0 net/ipv4/af_inet.c:719
 __sys_connect+0x357/0x490 net/socket.c:1664
 __do_sys_connect net/socket.c:1675 [inline]
 __se_sys_connect net/socket.c:1672 [inline]
 __x64_sys_connect+0x73/0xb0 net/socket.c:1672
 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:00007f83b5507c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457ec9
RDX: 0000000000000010 RSI: 0000000020ccb000 RDI: 0000000000000006
RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f83b55086d4
R13: 00000000004be30a R14: 00000000004ce6d8 R15: 00000000ffffffff
Modules linked in:
CR2: ffffed1bc3404006
---[ end trace 88a037c783301af1 ]---
RIP: 0010:dst_dev_put+0xa0/0x290 net/core/dst.c:171
Code: fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 e4 01 00 00 48 b8 00 00 00 00  
00 fc ff df 4c 8b 6b 08 49 8d 7d 38 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f  
85 b7 01 00 00 4d 8b 75 38 4d 89 e5 4d 85 f6 74 33
RSP: 0018:ffff88808dc47520 EFLAGS: 00010a07
RAX: dffffc0000000000 RBX: ffff8880a4b36806 RCX: ffffc9000c042000
RDX: 1ffff11bc3404006 RSI: ffffffff8625e0d3 RDI: ffff88de1a020037
RBP: ffff88808dc47540 R08: 1ffffd1ffff8e344 R09: fffff91ffff8e345
R10: fffff91ffff8e344 R11: ffffe8ffffc71a27 R12: ffff8a391080ffff
R13: ffff88de1a01ffff R14: 1ffff11011b88eb5 R15: ffff88808dc475f8
FS:  00007f83b5508700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed1bc3404006 CR3: 0000000065801000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
kobject: 'loop5' (000000006c9bdf3e): kobject_uevent_env
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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