From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753743AbbAGPJM (ORCPT ); Wed, 7 Jan 2015 10:09:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39572 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752233AbbAGPJK (ORCPT ); Wed, 7 Jan 2015 10:09:10 -0500 Message-ID: <1420643344.6345.7.camel@redhat.com> Subject: Re: [PATCH] vhost/net: length miscalculation From: Alex Williamson To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Greg Kurz , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Date: Wed, 07 Jan 2015 08:09:04 -0700 In-Reply-To: <1420620847-24477-1-git-send-email-mst@redhat.com> References: <1420620847-24477-1-git-send-email-mst@redhat.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2015-01-07 at 10:55 +0200, Michael S. Tsirkin wrote: > commit 8b38694a2dc8b18374310df50174f1e4376d6824 > vhost/net: virtio 1.0 byte swap > had this chunk: > - heads[headcount - 1].len += datalen; > + heads[headcount - 1].len = cpu_to_vhost32(vq, len - datalen); > > This adds datalen with the wrong sign, causing guest panics. > > Fixes: 8b38694a2dc8b18374310df50174f1e4376d6824 > Reported-by: Alex Williamson > Suggested-by: Greg Kurz > Signed-off-by: Michael S. Tsirkin > --- > > Alex, could you please confirm this fixes the crash for you? Confirmed, this works. Thanks, Alex > drivers/vhost/net.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > index 14419a8..d415d69 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -538,7 +538,7 @@ static int get_rx_bufs(struct vhost_virtqueue *vq, > ++headcount; > seg += in; > } > - heads[headcount - 1].len = cpu_to_vhost32(vq, len - datalen); > + heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen); > *iovcount = seg; > if (unlikely(log)) > *log_num = nlogs;