general protection fault in qfq_reset_qdisc (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ec822b3e Linux 4.14.214
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1428fd0b500000
kernel config: https://syzkaller.appspot.com/x/.config?x=c7d2eef63e7505
dashboard link: https://syzkaller.appspot.com/bug?extid=a18624cdd73fb19e5a38
compiler: gcc (GCC) 10.1.0-syz 20200507

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a18624...@syzkaller.appspotmail.com

device veth0_macvtap left promiscuous mode
device veth1_vlan left promiscuous mode
device veth0_vlan left promiscuous mode
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
Modules linked in:
CPU: 0 PID: 5 Comm: kworker/u4:0 Not tainted 4.14.214-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
task: ffff8880b5ff2140 task.stack: ffff8880b5ff8000
RIP: 0010:qfq_reset_qdisc+0x143/0x490 net/sched/sch_qfq.c:1463
RSP: 0018:ffff8880b5fff9b8 EFLAGS: 00010202
RAX: 0000000000000013 RBX: ffff8880a05a6c00 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffff888057f48a80 RDI: 0000000000000098
RBP: dffffc0000000000 R08: ffff8880b5ff2140 R09: dffffc0000000000
R10: 0000000000000000 R11: ffff8880b5ff2140 R12: 0000000000000000
R13: ffff8880a05a6c48 R14: ffffed10146994f0 R15: ffff888057f48a80
FS: 0000000000000000(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c02c32d000 CR3: 000000009dc7d000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
qdisc_destroy+0x104/0x310 net/sched/sch_generic.c:724
dev_shutdown+0x27a/0x43e net/sched/sch_generic.c:1001
rollback_registered_many+0x73a/0xba0 net/core/dev.c:7197
unregister_netdevice_many.part.0+0x18/0x2e0 net/core/dev.c:8285
unregister_netdevice_many net/core/dev.c:8284 [inline]
default_device_exit_batch+0x2d8/0x380 net/core/dev.c:8746
ops_exit_list+0xf9/0x150 net/core/net_namespace.c:145
cleanup_net+0x3b3/0x840 net/core/net_namespace.c:484
process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 73 5f fb 4c 8d 6b 48 4c 89 e8 48 c1 e8 03 80 3c 28 00 0f 85 41 02 00 00 4c 8b 63 48 49 8d bc 24 98 00 00 00 48 89 f8 48 c1 e8 03 <0f> b6 04 28 84 c0 74 08 3c 03 0f 8e 35 02 00 00 41 8b 84 24 98
RIP: qfq_reset_qdisc+0x143/0x490 net/sched/sch_qfq.c:1463 RSP: ffff8880b5fff9b8
---[ end trace 1201e69eec0e9e0d ]---


---
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 syzk...@googlegroups.com.

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

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.