Subject: [syzbot] [net?] WARNING in ip_tunnel_delete_nets (2)

From: syzbot <[email-masked]>
Date: Sun, 13 Aug 2023 20:32:47 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    2ccdd1b13c59 Linux 6.5-rc6
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16e56ef7a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8fc59e2140295873
dashboard link: https://syzkaller.appspot.com/bug?extid=b7a5f4ad84b87ee1b3ae
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e6e598627dd6/disk-2ccdd1b1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/486c6739d779/vmlinux-2ccdd1b1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5da0f3ac1d56/bzImage-2ccdd1b1.xz

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

------------[ cut here ]------------
WARNING: CPU: 0 PID: 18960 at net/core/dev.c:10876 unregister_netdevice_many_notify+0x14d8/0x19a0 net/core/dev.c:10876
Modules linked in:
CPU: 0 PID: 18960 Comm: kworker/u4:2 Not tainted 6.5.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Workqueue: netns cleanup_net
RIP: 0010:unregister_netdevice_many_notify+0x14d8/0x19a0 net/core/dev.c:10876
Code: b4 1a 00 00 48 c7 c6 e0 0e 81 8b 48 c7 c7 20 0f 81 8b c6 05 11 62 6c 06 01 e8 44 21 23 f9 0f 0b e9 64 f7 ff ff e8 d8 5f 5c f9 <0f> 0b e9 3b f7 ff ff e8 cc 8f af f9 e9 fc ec ff ff 4c 89 e7 e8 1f
RSP: 0018:ffffc900002cfa28 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 000000007cf48c01 RCX: 0000000000000000
RDX: ffff8880391ba080 RSI: ffffffff8828c0e8 RDI: 0000000000000001
RBP: ffff888077db4000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 000000000000004e R12: ffff88802380c900
R13: 0000000000000000 R14: 0000000000000002 R15: ffff88802380c900
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c001ac9010 CR3: 000000001ea93000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ip_tunnel_delete_nets+0x2bb/0x3a0 net/ipv4/ip_tunnel.c:1144
 ops_exit_list+0x125/0x170 net/core/net_namespace.c:175
 cleanup_net+0x505/0xb20 net/core/net_namespace.c:614
 process_one_work+0xaa2/0x16f0 kernel/workqueue.c:2600
 worker_thread+0x687/0x1110 kernel/workqueue.c:2751
 kthread+0x33a/0x430 kernel/kthread.c:389
 ret_from_fork+0x2c/0x70 arch/x86/kernel/process.c:145
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>

---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at [email-masked].

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the bug is already fixed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to change bug's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup