lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <59d61db8-8d3a-44f1-b664-d4649615afc7@oracle.com>
Date: Tue, 30 Apr 2024 20:01:11 -0500
From: Mike Christie <michael.christie@...cle.com>
To: Hillf Danton <hdanton@...a.com>
Cc: "Michael S. Tsirkin" <mst@...hat.com>, Edward Adam Davis
 <eadavis@...com>,
        syzbot+98edc2df894917b3431f@...kaller.appspotmail.com,
        jasowang@...hat.com, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        virtualization@...ts.linux.dev
Subject: Re: [PATCH next] vhost_task: after freeing vhost_task it should not
 be accessed in vhost_task_fn

On 4/30/24 7:15 PM, Hillf Danton wrote:
> On Tue, Apr 30, 2024 at 11:23:04AM -0500, Mike Christie wrote:
>> On 4/30/24 8:05 AM, Edward Adam Davis wrote:
>>>  static int vhost_task_fn(void *data)
>>>  {
>>>  	struct vhost_task *vtsk = data;
>>> @@ -51,7 +51,7 @@ static int vhost_task_fn(void *data)
>>>  			schedule();
>>>  	}
>>>  
>>> -	mutex_lock(&vtsk->exit_mutex);
>>> +	mutex_lock(&exit_mutex);
>>>  	/*
>>>  	 * If a vhost_task_stop and SIGKILL race, we can ignore the SIGKILL.
>>>  	 * When the vhost layer has called vhost_task_stop it's already stopped
>>> @@ -62,7 +62,7 @@ static int vhost_task_fn(void *data)
>>>  		vtsk->handle_sigkill(vtsk->data);
>>>  	}
>>>  	complete(&vtsk->exited);
>>> -	mutex_unlock(&vtsk->exit_mutex);
>>> +	mutex_unlock(&exit_mutex);
>>>  
>>
>> Edward, thanks for the patch. I think though I just needed to swap the
>> order of the calls above.
>>
>> Instead of:
>>
>> complete(&vtsk->exited);
>> mutex_unlock(&vtsk->exit_mutex);
>>
>> it should have been:
>>
>> mutex_unlock(&vtsk->exit_mutex);
>> complete(&vtsk->exited);
> 
> JFYI Edward did it [1]
> 
> [1] https://lore.kernel.org/lkml/tencent_546DA49414E876EEBECF2C78D26D242EE50A@qq.com/

Thanks.

I tested the code with that change and it no longer triggers the UAF.

I've fixed up the original patch that had the bug and am going to
resubmit the patchset like how Michael requested.


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ