From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751927AbeC2EUg (ORCPT ); Thu, 29 Mar 2018 00:20:36 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:45176 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750707AbeC2EUe (ORCPT ); Thu, 29 Mar 2018 00:20:34 -0400 Date: Thu, 29 Mar 2018 07:20:30 +0300 From: "Michael S. Tsirkin" To: Jason Wang Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Darren Kenny Subject: Re: [PATCH net V2] vhost: correctly remove wait queue during poll failure Message-ID: <20180329071801-mutt-send-email-mst@kernel.org> References: <1522155052-13347-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1522155052-13347-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 27, 2018 at 08:50:52PM +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 switching to use vhost_poll_stop() which zeros poll->wqh after > removing poll from waitqueue to make sure it won't be freed twice. > > Cc: Darren Kenny > Reported-by: syzbot+c0272972b01b872e604a@syzkaller.appspotmail.com > Fixes: 2b8b328b61c79 ("vhost_net: handle polling errors when setting backend") > Signed-off-by: Jason Wang OK with this the only bug we have is where get user pages returns 0 (Reported-by: syzbot+6304bf97ef436580fede@syzkaller.appspotmail.com) > --- > Changes from V1: > - tweak the commit log for to match the code > --- > 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