From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: [PATCH net] vhost/net: fix heads usage of ubuf_info Date: Sun, 17 Mar 2013 14:46:09 +0200 Message-ID: <20130317124609.GA25967@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Nicholas A. Bellinger" , virtualization@lists.linux-foundation.org, stable@kernel.org, Basil Gor To: "David S. Miller" Return-path: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org ubuf info allocator uses guest controlled head as an index, so a malicious guest could put the same head entry in the ring twice, and we will get two callbacks on the same value. To fix use upend_idx which is guaranteed to be unique. Reported-by: Rusty Russell Signed-off-by: Michael S. Tsirkin Cc: stable@kernel.org --- Rusty's working on switching to allocating ubufs dynamically but that's not 3.9 material. This patch is against latest net master, needed for 3.9-rc2 and older kernels. drivers/vhost/net.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 959b1cd..ec6fb3f 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -339,7 +339,8 @@ static void handle_tx(struct vhost_net *net) msg.msg_controllen = 0; ubufs = NULL; } else { - struct ubuf_info *ubuf = &vq->ubuf_info[head]; + struct ubuf_info *ubuf; + ubuf = vq->ubuf_info + vq->upend_idx; vq->heads[vq->upend_idx].len = VHOST_DMA_IN_PROGRESS; -- MST