[syzbot] [net?] WARNING in unregister_vlan_dev

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 048c796beb6e ipv6: adjust ndisc_is_useropt() to also retur..
git tree: net
console+strace: https://syzkaller.appspot.com/x/log.txt?x=122a53aba80000
kernel config: https://syzkaller.appspot.com/x/.config?x=fa5bd4cd5ab6259d
dashboard link: https://syzkaller.appspot.com/bug?extid=662f783a5cdf3add2719
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1604a23da80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15261ffda80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bf6b84b5998f/disk-048c796b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4000dee89ebe/vmlinux-048c796b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b700ee9bd306/bzImage-048c796b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+662f78...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 5027 at net/core/dev.c:10876 unregister_netdevice_many_notify+0x14d8/0x19a0 net/core/dev.c:10876
Modules linked in:
CPU: 0 PID: 5027 Comm: syz-executor906 Not tainted 6.5.0-rc4-syzkaller-00248-g048c796beb6e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
RIP: 0010:unregister_netdevice_many_notify+0x14d8/0x19a0 net/core/dev.c:10876
Code: b4 1a 00 00 48 c7 c6 e0 18 81 8b 48 c7 c7 20 19 81 8b c6 05 ab 19 6c 06 01 e8 b4 22 23 f9 0f 0b e9 64 f7 ff ff e8 68 60 5c f9 <0f> 0b e9 3b f7 ff ff e8 fc 68 b0 f9 e9 fc ec ff ff 4c 89 e7 e8 4f
RSP: 0018:ffffc900039bfae0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000027f95e01 RCX: 0000000000000000
RDX: ffff88802d241dc0 RSI: ffffffff8829a7b8 RDI: 0000000000000001
RBP: ffff88807c680000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffffffff8a40008b R12: ffff888029882e80
R13: 0000000000000000 R14: 0000000000000002 R15: ffff888029882e80
FS: 0000555555f8f380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020002800 CR3: 000000007f16b000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
unregister_netdevice_many net/core/dev.c:10906 [inline]
unregister_netdevice_queue+0x2e5/0x3c0 net/core/dev.c:10786
unregister_vlan_dev+0x2a9/0x580 net/8021q/vlan.c:118
vlan_ioctl_handler+0x387/0xa80 net/8021q/vlan.c:627
sock_ioctl+0x4b0/0x6e0 net/socket.c:1271
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f29480b4419
Code: 48 83 c4 28 c3 e8 d7 19 00 00 0f 1f 80 00 00 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdb9d37898 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f2948101390 RCX: 00007f29480b4419
RDX: 0000000020002800 RSI: 0000000000008982 RDI: 0000000000000004
RBP: 0000000000000003 R08: 0000555500000000 R09: 0000555500000000
R10: 0000555500000000 R11: 0000000000000246 R12: 00007ffdb9d378e0
R13: 00007ffdb9d378b0 R14: 0000000000000001 R15: 00007ffdb9d378e0
</TASK>


---
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[Hillf Danton]

On Fri, 11 Aug 2023 06:57:06 -0700

> HEAD commit: 048c796beb6e ipv6: adjust ndisc_is_useropt() to also retur..
> git tree: net

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15261ffda80000

Try to revert 718cb09aaa6f

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git 048c796beb6e

--- x/net/8021q/vlan.c
+++ y/net/8021q/vlan.c
@@ -384,7 +384,7 @@ static int vlan_device_event(struct noti
dev->name);
vlan_vid_add(dev, htons(ETH_P_8021Q), 0);
}
- if (event == NETDEV_DOWN)
+ if (event == NETDEV_DOWN && (dev->features & NETIF_F_HW_VLAN_CTAG_FILTER))
vlan_vid_del(dev, htons(ETH_P_8021Q), 0);

vlan_info = rtnl_dereference(dev->vlan_info);
@@ -486,6 +486,7 @@ static int vlan_device_event(struct noti
break;
}
unregister_netdevice_many(&list);
+ vlan_vid_del(dev, htons(ETH_P_8021Q), 0);
break;

case NETDEV_PRE_TYPE_CHANGE:
--

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+662f78...@syzkaller.appspotmail.com

Tested on:

commit: 048c796b ipv6: adjust ndisc_is_useropt() to also retur..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=118377fda80000

kernel config: https://syzkaller.appspot.com/x/.config?x=fa5bd4cd5ab6259d
dashboard link: https://syzkaller.appspot.com/bug?extid=662f783a5cdf3add2719
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=165f1d63a80000

Note: testing is done by a robot and is best-effort only.

[syzbot]

syzbot has bisected this issue to:

commit 718cb09aaa6fa78cc8124e9517efbc6c92665384
Author: Vlad Buslov <vla...@nvidia.com>
Date: Tue Aug 8 09:35:21 2023 +0000

vlan: Fix VLAN 0 memory leak

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=12ac8d6fa80000
start commit: 048c796beb6e ipv6: adjust ndisc_is_useropt() to also retur..
git tree: net
final oops: https://syzkaller.appspot.com/x/report.txt?x=11ac8d6fa80000
console output: https://syzkaller.appspot.com/x/log.txt?x=16ac8d6fa80000

kernel config: https://syzkaller.appspot.com/x/.config?x=fa5bd4cd5ab6259d
dashboard link: https://syzkaller.appspot.com/bug?extid=662f783a5cdf3add2719

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1604a23da80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15261ffda80000

Reported-by: syzbot+662f78...@syzkaller.appspotmail.com
Fixes: 718cb09aaa6f ("vlan: Fix VLAN 0 memory leak")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection