general protection fault in drop_sysctl_table

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9f84340f Linux 4.19.196
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17fabcd2300000
kernel config: https://syzkaller.appspot.com/x/.config?x=abf37bdf4eb59b8e
dashboard link: https://syzkaller.appspot.com/bug?extid=f0a48b7cbebfab3a7346

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+f0a48b...@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: 23 Comm: kworker/u4:1 Not tainted 4.19.196-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
RIP: 0010:erase_header fs/proc/proc_sysctl.c:206 [inline]
RIP: 0010:start_unregistering fs/proc/proc_sysctl.c:331 [inline]
RIP: 0010:drop_sysctl_table+0x539/0x9e0 fs/proc/proc_sysctl.c:1635
Code: 88 ff 48 c7 c7 60 de 06 8a e8 33 37 55 06 4c 89 f0 48 c1 e8 03 42 80 3c 28 00 0f 85 2f 04 00 00 49 8b 1e 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 0d 04 00 00 48 83 3b 00 0f 84 9f 00 00 00 49
RSP: 0018:ffff8880b5047760 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff814bdc4b
RDX: 1ffffffff140dbce RSI: 0000000000000004 RDI: ffffffff8a06de60
RBP: 0000000000000000 R08: 0000000000000001 R09: fffffbfff140dbcc
R10: ffffffff8a06de63 R11: 0000000000000000 R12: 0000000000000001
R13: dffffc0000000000 R14: ffff888000100280 R15: ffff888219696400
FS: 0000000000000000(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd20fafcc8 CR3: 00000000a8248000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
unregister_sysctl_table fs/proc/proc_sysctl.c:1677 [inline]
unregister_sysctl_table+0xbd/0x190 fs/proc/proc_sysctl.c:1652
__devinet_sysctl_unregister net/ipv4/devinet.c:2367 [inline]
devinet_sysctl_unregister net/ipv4/devinet.c:2395 [inline]
inetdev_destroy net/ipv4/devinet.c:317 [inline]
inetdev_event+0x6fe/0x1270 net/ipv4/devinet.c:1545
notifier_call_chain+0xc0/0x230 kernel/notifier.c:93
call_netdevice_notifiers net/core/dev.c:1762 [inline]
rollback_registered_many+0x83e/0xe70 net/core/dev.c:8188
unregister_netdevice_many.part.0+0x1a/0x300 net/core/dev.c:9316
unregister_netdevice_many+0x36/0x50 net/core/dev.c:9315
vti6_exit_batch_net+0x40f/0x620 net/ipv6/ip6_vti.c:1178
ops_exit_list+0xf9/0x150 net/core/net_namespace.c:156
cleanup_net+0x3b4/0x8b0 net/core/net_namespace.c:553
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Modules linked in:
---[ end trace c46b4c95e6df46af ]---
RIP: 0010:erase_header fs/proc/proc_sysctl.c:206 [inline]
RIP: 0010:start_unregistering fs/proc/proc_sysctl.c:331 [inline]
RIP: 0010:drop_sysctl_table+0x539/0x9e0 fs/proc/proc_sysctl.c:1635
Code: 88 ff 48 c7 c7 60 de 06 8a e8 33 37 55 06 4c 89 f0 48 c1 e8 03 42 80 3c 28 00 0f 85 2f 04 00 00 49 8b 1e 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 0d 04 00 00 48 83 3b 00 0f 84 9f 00 00 00 49
RSP: 0018:ffff8880b5047760 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff814bdc4b
RDX: 1ffffffff140dbce RSI: 0000000000000004 RDI: ffffffff8a06de60
RBP: 0000000000000000 R08: 0000000000000001 R09: fffffbfff140dbcc
R10: ffffffff8a06de63 R11: 0000000000000000 R12: 0000000000000001
R13: dffffc0000000000 R14: ffff888000100280 R15: ffff888219696400
FS: 0000000000000000(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd20fafcc8 CR3: 0000000009e6d000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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[syzbot]

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