From: Jason Wang <jasowang@redhat.com>
To: mst@redhat.com, kvm@vger.kernel.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] vhost: correctly remove wait queue during poll failure
Date: Tue, 27 Mar 2018 17:43:14 +0800 [thread overview]
Message-ID: <b1576bcf-652a-7c1a-9d77-db54931ab979@redhat.com> (raw)
In-Reply-To: <20180327092811.ikvssyxgb74nucb4@dhcp-10-175-199-170.vpn.oracle.com>
On 2018年03月27日 17:28, Darren Kenny wrote:
> Hi Jason,
>
> On Tue, Mar 27, 2018 at 11:47:22AM +0800, Jason Wang wrote:
>> We tried to remove vq poll from wait queue, but do not check whether
>> or not it was in a list before. This will lead double free. Fixing
>> this by checking poll->wqh to make sure it was in a list.
>
> This text seems at odds with the code below, instead of checking
> poll-whq, you are removing that check...
>
> Maybe the text needs rewording?
Yes, I admit it's bad, thanks for pointing out.
How about:
"Fixing this by switching to use vhost_poll_stop() which zeros poll->wqh
after removing poll from waitqueue to make sure it won't be freed twice."
Thanks
>
> Thanks,
>
> Darren.
>
>>
>> Reported-by: syzbot+c0272972b01b872e604a@syzkaller.appspotmail.com
>> Fixes: 2b8b328b61c79 ("vhost_net: handle polling errors when setting
>> backend")
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>> drivers/vhost/vhost.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
>> index 1b3e8d2d..5d5a9d9 100644
>> --- a/drivers/vhost/vhost.c
>> +++ b/drivers/vhost/vhost.c
>> @@ -212,8 +212,7 @@ int vhost_poll_start(struct vhost_poll *poll,
>> struct file *file)
>> if (mask)
>> vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask));
>> if (mask & EPOLLERR) {
>> - if (poll->wqh)
>> - remove_wait_queue(poll->wqh, &poll->wait);
>> + vhost_poll_stop(poll);
>> ret = -EINVAL;
>> }
>>
>> --
>> 2.7.4
>>
next prev parent reply other threads:[~2018-03-27 9:43 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-27 3:47 [PATCH net] vhost: correctly remove wait queue during poll failure Jason Wang
2018-03-27 9:28 ` Darren Kenny
2018-03-27 9:43 ` Jason Wang
2018-03-27 9:43 ` Jason Wang [this message]
2018-03-27 13:58 ` Michael S. Tsirkin
2018-03-27 13:58 ` Michael S. Tsirkin
2018-03-27 3:47 Jason Wang
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