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

[Pengfei Xu <pengfei.xu@intel.com>]

On 2024-02-21 at 13:41:54 +0800, Kuniyuki Iwashima wrote:
> From: Pengfei Xu <pengfei.xu@intel.com>
> 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@amazon.com/

Thanks for your link and patch!
I tried the above patch on top of v6.8-rc5, this issue could not be reproduced.
It's fixed by above patch.

Best Regards,
Thanks!