Re: [PATCH 1/1] vhost: Protect the virtqueue from being cleared whilst still in use

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Lee Jones <lee.jones@linaro.org>
Cc: jasowang@redhat.com, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, stable@vger.kernel.org,
	syzbot+adc3cb32385586bec859@syzkaller.appspotmail.com
Subject: Re: [PATCH 1/1] vhost: Protect the virtqueue from being cleared whilst still in use
Date: Tue, 8 Mar 2022 06:07:26 -0500	[thread overview]
Message-ID: <20220308060705-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <YicNXOlH8al/Rlk3@google.com>

On Tue, Mar 08, 2022 at 08:01:32AM +0000, Lee Jones wrote:
> On Mon, 07 Mar 2022, Michael S. Tsirkin wrote:
> 
> > On Mon, Mar 07, 2022 at 07:17:57PM +0000, Lee Jones wrote:
> > > vhost_vsock_handle_tx_kick() already holds the mutex during its call
> > > to vhost_get_vq_desc().  All we have to do here is take the same lock
> > > during virtqueue clean-up and we mitigate the reported issues.
> > 
> > Pls just basically copy the code comment here. this is just confuses.
> > 
> > > Also WARN() as a precautionary measure.  The purpose of this is to
> > > capture possible future race conditions which may pop up over time.
> > > 
> > > Link: https://syzkaller.appspot.com/bug?extid=279432d30d825e63ba00
> > 
> > And this is a bug we already fixed, right?
> 
> Well, this was the bug I set out to fix.
> 
> I didn't know your patch was in flight at the time.
> 
> > > Cc: <stable@vger.kernel.org>
> > > Reported-by: syzbot+adc3cb32385586bec859@syzkaller.appspotmail.com
> > 
> > not really applicable anymore ...
> 
> I can remove these if it helps.

yes let's do that pls.

> -- 
> Lee Jones [李琼斯]
> Principal Technical Lead - Developer Services
> Linaro.org │ Open source software for Arm SoCs
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