Re: [syzbot] WARNING: suspicious RCU usage in __dev_queue_xmit

From: Florian Westphal
Date: Mon Jan 10 2022 - 06:50:34 EST


syzbot <syzbot+e163f2ff7c3f7efd8203@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 4c375272fb0b Merge branch 'net-add-preliminary-netdev-refc..
> git tree: net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=164749a9b00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=2b8e24e3a80e3875
> dashboard link: https://syzkaller.appspot.com/bug?extid=e163f2ff7c3f7efd8203
> 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=11493641b00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11ac6aceb00000

> include/linux/netfilter_netdev.h:97 suspicious rcu_dereference_check() usage!

#syz fix: netfilter: egress: avoid a lockdep splat