linux-kernel - Re: [PATCH v5.10] vhost-scsi: protect vq->log

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Message-ID: <10baccb6-f00e-4911-a3ec-8d28aec67b13@huawei.com>
Date: Mon, 14 Jul 2025 17:42:08 +0800
From: "zhengxinyu (E)" <zhengxinyu6@...wei.com>
To: Greg KH <gregkh@...uxfoundation.org>
CC: <mst@...hat.com>, <jasowang@...hat.com>, <pbonzini@...hat.com>,
	<stefanha@...hat.com>, <virtualization@...ts.linux-foundation.org>,
	<kvm@...r.kernel.org>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>
Subject: Re: [PATCH v5.10] vhost-scsi: protect vq->log_used with vq->mutex



On 7/10/2025 9:41 PM, Greg KH wrote:
> On Wed, Jul 02, 2025 at 08:29:45AM +0000, Xinyu Zheng wrote:
>> From: Dongli Zhang <dongli.zhang@...cle.com>
>>
>> [ Upstream commit f591cf9fce724e5075cc67488c43c6e39e8cbe27 ]
>>
>> The vhost-scsi completion path may access vq->log_base when vq->log_used is
>> already set to false.
>>
>>      vhost-thread                       QEMU-thread
>>
>> vhost_scsi_complete_cmd_work()
>> -> vhost_add_used()
>>     -> vhost_add_used_n()
>>        if (unlikely(vq->log_used))
>>                                        QEMU disables vq->log_used
>>                                        via VHOST_SET_VRING_ADDR.
>>                                        mutex_lock(&vq->mutex);
>>                                        vq->log_used = false now!
>>                                        mutex_unlock(&vq->mutex);
>>
>> 				      QEMU gfree(vq->log_base)
>>          log_used()
>>          -> log_write(vq->log_base)
>>
>> Assuming the VMM is QEMU. The vq->log_base is from QEMU userpace and can be
>> reclaimed via gfree(). As a result, this causes invalid memory writes to
>> QEMU userspace.
>>
>> The control queue path has the same issue.
>>
>> CVE-2025-38074
> 
> This is not needed.
> 
>> Cc: stable@...r.kernel.org#5.10.x
> 
> What about 5.15.y and 6.1.y?  We can't take a patch just for 5.10 as
> that would cause regressions, right?
> 
> Please provide all relevant backports and I will be glad to queue them
> up then.  I'll drop this from my queue for now, thanks.
> 
> greg k-h

Sorry for forgetting the 5.15.y and 6.1.y patches. I will resend it as 
soon as possible. Thanks for pointing out my patch format error.

Xinyu Zheng