From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: [PATCH net V2 3/4] virtio-net: correctly check num_buf during err path Date: Tue, 22 May 2018 11:44:30 +0800 Message-ID: <1526960671-11782-4-git-send-email-jasowang@redhat.com> References: <1526960671-11782-1-git-send-email-jasowang@redhat.com> Cc: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: mst@redhat.com, jasowang@redhat.com Return-path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:50704 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752556AbeEVDov (ORCPT ); Mon, 21 May 2018 23:44:51 -0400 In-Reply-To: <1526960671-11782-1-git-send-email-jasowang@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: If we successfully linearize the packet, num_buf will be set to zero which may confuse error handling path which assumes num_buf is at least 1 and this can lead the code tries to pop the descriptor of next buffer. Fixing this by checking num_buf against 1 before decreasing. Fixes: 4941d472bf95 ("virtio-net: do not reset during XDP set") Signed-off-by: Jason Wang --- drivers/net/virtio_net.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 6260d65..326e247 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -875,7 +875,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, rcu_read_unlock(); err_skb: put_page(page); - while (--num_buf) { + while (num_buf-- > 1) { buf = virtqueue_get_buf(rq->vq, &len); if (unlikely(!buf)) { pr_debug("%s: rx error: %d buffers missing\n", -- 2.7.4