Re: [Syzkaller & bisect] There is BUG: soft lockup after sendmsg syscall in v6.8-rc4

[Kuniyuki Iwashima]

From: Pengfei Xu <pengfei.xu@xxxxxxxxx>
Date: Wed, 21 Feb 2024 10:30:05 +0800
> Hi Kuniyuki Iwashima and kernel experts,
> 
> Greeting!
> There is BUG: soft lockup after sendmsg syscall in v6.8-rc4 in guest.
> 
> All detailed info: https://github.com/xupengfe/syzkaller_logs/tree/main/240220_161242_softlockup
> Syzkaller reproduced code: https://github.com/xupengfe/syzkaller_logs/blob/main/240220_161242_softlockup/repro.c
> Syzkaller syscall reproduced steps: https://github.com/xupengfe/syzkaller_logs/blob/main/240220_161242_softlockup/repro.prog
> Kconfig(need make olddefconfig): https://github.com/xupengfe/syzkaller_logs/blob/main/240220_161242_softlockup/kconfig_origin
> Bisect info: https://github.com/xupengfe/syzkaller_logs/blob/main/240220_161242_softlockup/bisect_info.log
> v6.8-rc4 issue dmesg: https://github.com/xupengfe/syzkaller_logs/blob/main/240220_161242_softlockup/841c35169323cd833294798e58b9bf63fa4fa1de_dmesg.log
> bzImage_v6.8-rc4: https://github.com/xupengfe/syzkaller_logs/raw/main/240220_161242_softlockup/bzImage_v6.8-rc4.tar.gz
> 
> Bisected and found first bad commit:
> "
> 1279f9d9dec2 af_unix: Call kfree_skb() for dead unix_(sk)->oob_skb in GC.
> "

Thanks for the report.

I think syzbot reported the same issue.
https://syzkaller.appspot.com/bug?extid=ecab4d36f920c3574bf9

Could you try this patch ?
https://lore.kernel.org/netdev/20240219174657.6047-1-kuniyu@xxxxxxxxxx/