Subject: Re: [syzbot] WARNING in mroute_clean_tables

From: syzbot <[email-masked]>
Date: Thu, 10 Feb 2022 06:05:18 -0800

syzbot has found a reproducer for the following issue on:

HEAD commit:    e5313968c41b Merge branch 'Split bpf_sk_lookup remote_port..
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=141c859a700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c40b67275bfe2a58
dashboard link: https://syzkaller.appspot.com/bug?extid=a7c030a05218db921de5
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=130486f8700000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16d9f758700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

------------[ cut here ]------------
RTNL: assertion failed at net/core/dev.c (10367)
WARNING: CPU: 1 PID: 3674 at net/core/dev.c:10367 unregister_netdevice_many+0x1246/0x1850 net/core/dev.c:10367
Modules linked in:
CPU: 1 PID: 3674 Comm: syz-executor165 Not tainted 5.16.0-syzkaller-11655-ge5313968c41b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:unregister_netdevice_many+0x1246/0x1850 net/core/dev.c:10367
Code: 0f 85 9b ee ff ff e8 59 f1 4a fa ba 7f 28 00 00 48 c7 c6 00 90 ae 8a 48 c7 c7 40 90 ae 8a c6 05 0e a1 51 06 01 e8 3c 8a d8 01 <0f> 0b e9 70 ee ff ff e8 2e f1 4a fa 4c 89 e7 e8 c6 22 59 fa e9 ee
RSP: 0018:ffffc90003adf6e0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff888075bf8000 RSI: ffffffff815fa058 RDI: fffff5200075bece
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815f3dbe R11: 0000000000000000 R12: 00000000fffffff4
R13: dffffc0000000000 R14: ffffc90003adf750 R15: ffff888070f9c000
FS:  00007f8cda422700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8cda4229d0 CR3: 0000000071e66000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 mroute_clean_tables+0x244/0xb40 net/ipv6/ip6mr.c:1509
 ip6mr_free_table net/ipv6/ip6mr.c:389 [inline]
 ip6mr_rules_init net/ipv6/ip6mr.c:246 [inline]
 ip6mr_net_init net/ipv6/ip6mr.c:1306 [inline]
 ip6mr_net_init+0x3f0/0x4e0 net/ipv6/ip6mr.c:1298
 ops_init+0xaf/0x470 net/core/net_namespace.c:140
 setup_net+0x54f/0xbb0 net/core/net_namespace.c:331
 copy_net_ns+0x318/0x760 net/core/net_namespace.c:475
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 copy_namespaces+0x391/0x450 kernel/nsproxy.c:178
 copy_process+0x2e15/0x7310 kernel/fork.c:2167
 kernel_clone+0xe7/0xab0 kernel/fork.c:2555
 __do_sys_clone+0xc8/0x110 kernel/fork.c:2672
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f8cda472169
Code: Unable to access opcode bytes at RIP 0x7f8cda47213f.
RSP: 002b:00007f8cda4222f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f8cda4fb4e0 RCX: 00007f8cda472169
RDX: 0000000020000080 RSI: 0000000020000050 RDI: 0000000046000080
RBP: 00007f8cda4c82fc R08: 0000000020000100 R09: 0000000000000000
R10: 00000000200000c0 R11: 0000000000000246 R12: 00007f8cda4c82ed
R13: 2bcc52a5f498fa8d R14: 000000344059e000 R15: 00007f8cda4fb4e8
 </TASK>