From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36649) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ve13x-00065P-7n for qemu-devel@nongnu.org; Wed, 06 Nov 2013 06:14:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ve13s-0003RK-RS for qemu-devel@nongnu.org; Wed, 06 Nov 2013 06:14:17 -0500 Date: Wed, 6 Nov 2013 13:17:04 +0200 From: "Michael S. Tsirkin" Message-ID: <20131106111704.GA29363@redhat.com> References: <1383728288-28469-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1383728288-28469-1-git-send-email-jasowang@redhat.com> Subject: Re: [Qemu-devel] [PATCH] virtio-net: only delete bh that existed List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang Cc: qemu-devel@nongnu.org, aliguori@amazon.com, qemu-stable@nongnu.org On Wed, Nov 06, 2013 at 04:58:08PM +0800, Jason Wang wrote: > We delete without check whether it existed during exit. This will lead NULL > pointer deference since it was created conditionally depends on guest driver > status and features. So add a check of existence before trying to delete it. > > Cc: qemu-stable@nongnu.org > Signed-off-by: Jason Wang Reviewed-by: Michael S. Tsirkin Looks like the bug was introduced by: commit 17ec5a8686143da66208273d355f2eeb09807614 Author: KONRAD Frederic Date: Thu Apr 11 16:29:57 2013 +0200 virtio-net: add the virtio-net device. Before that we had a single bh and created/destroyed that unconditionally. Is this a correct analysis? > --- > hw/net/virtio-net.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > index 22dbd05..ae51d96 100644 > --- a/hw/net/virtio-net.c > +++ b/hw/net/virtio-net.c > @@ -1601,7 +1601,7 @@ static int virtio_net_device_exit(DeviceState *qdev) > if (q->tx_timer) { > timer_del(q->tx_timer); > timer_free(q->tx_timer); > - } else { > + } else if (q->tx_bh) { > qemu_bh_delete(q->tx_bh); > } > } > -- > 1.8.3.2