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From: "Michael S. Tsirkin" <mst@redhat.com>
To: netdev@vger.kernel.org
Cc: Michael Dalton <mwdalton@google.com>,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	Eric Dumazet <edumazet@google.com>,
	David Miller <davem@davemloft.net>
Subject: [PATCH stable 1/2] virtio_net: fix error handling for mergeable buffers
Date: Wed, 25 Dec 2013 16:56:21 +0200	[thread overview]
Message-ID: <1387983339-1172-2-git-send-email-mst@redhat.com> (raw)
In-Reply-To: <1387983339-1172-1-git-send-email-mst@redhat.com>

Eric Dumazet noticed that if we encounter an error
when processing a mergeable buffer, we don't
dequeue all of the buffers from this packet,
the result is almost sure to be loss of networking.

Jason Wang noticed that we also leak a page and that we don't decrement
the rq buf count, so we won't repost buffers (a resource leak).

Fix both issues.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michael Dalton <mwdalton@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: David S. Miller <davem@davemloft.net>

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

(cherry picked from commit 8fc3b9e9a229778e5af3aa453c44f1a3857ba769)
---
 drivers/net/virtio_net.c | 66 +++++++++++++++++++++++++++++++++---------------
 1 file changed, 46 insertions(+), 20 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 9fbdfcd..435076f 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -297,26 +297,33 @@ static struct sk_buff *page_to_skb(struct receive_queue *rq,
 	return skb;
 }
 
-static int receive_mergeable(struct receive_queue *rq, struct sk_buff *skb)
+static struct sk_buff *receive_mergeable(struct net_device *dev,
+					 struct receive_queue *rq,
+					 void *buf,
+					 unsigned int len)
 {
-	struct skb_vnet_hdr *hdr = skb_vnet_hdr(skb);
-	struct page *page;
-	int num_buf, i, len;
+	struct skb_vnet_hdr *hdr = page_address(buf);
+	int num_buf = hdr->mhdr.num_buffers;
+	struct page *page = buf;
+	struct sk_buff *skb = page_to_skb(rq, page, len);
+	int i;
+
+	if (unlikely(!skb))
+		goto err_skb;
 
-	num_buf = hdr->mhdr.num_buffers;
 	while (--num_buf) {
 		i = skb_shinfo(skb)->nr_frags;
 		if (i >= MAX_SKB_FRAGS) {
 			pr_debug("%s: packet too long\n", skb->dev->name);
 			skb->dev->stats.rx_length_errors++;
-			return -EINVAL;
+			return NULL;
 		}
 		page = virtqueue_get_buf(rq->vq, &len);
 		if (!page) {
-			pr_debug("%s: rx error: %d buffers missing\n",
-				 skb->dev->name, hdr->mhdr.num_buffers);
-			skb->dev->stats.rx_length_errors++;
-			return -EINVAL;
+			pr_debug("%s: rx error: %d buffers %d missing\n",
+				 dev->name, hdr->mhdr.num_buffers, num_buf);
+			dev->stats.rx_length_errors++;
+			goto err_buf;
 		}
 
 		if (len > PAGE_SIZE)
@@ -326,7 +333,25 @@ static int receive_mergeable(struct receive_queue *rq, struct sk_buff *skb)
 
 		--rq->num;
 	}
-	return 0;
+	return skb;
+err_skb:
+	give_pages(rq, page);
+	while (--num_buf) {
+		buf = virtqueue_get_buf(rq->vq, &len);
+		if (unlikely(!buf)) {
+			pr_debug("%s: rx error: %d buffers missing\n",
+				 dev->name, num_buf);
+			dev->stats.rx_length_errors++;
+			break;
+		}
+		page = buf;
+		give_pages(rq, page);
+		--rq->num;
+	}
+err_buf:
+	dev->stats.rx_dropped++;
+	dev_kfree_skb(skb);
+	return NULL;
 }
 
 static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len)
@@ -354,17 +379,18 @@ static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len)
 		skb_trim(skb, len);
 	} else {
 		page = buf;
-		skb = page_to_skb(rq, page, len);
-		if (unlikely(!skb)) {
-			dev->stats.rx_dropped++;
-			give_pages(rq, page);
-			return;
-		}
-		if (vi->mergeable_rx_bufs)
-			if (receive_mergeable(rq, skb)) {
-				dev_kfree_skb(skb);
+		if (vi->mergeable_rx_bufs) {
+			skb = receive_mergeable(dev, rq, page, len);
+			if (unlikely(!skb))
+				return;
+		} else {
+			skb = page_to_skb(rq, page, len);
+			if (unlikely(!skb)) {
+				dev->stats.rx_dropped++;
+				give_pages(rq, page);
 				return;
 			}
+		}
 	}
 
 	hdr = skb_vnet_hdr(skb);
-- 
MST

  reply	other threads:[~2013-12-25 14:56 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-25 14:56 [PATCH stable 0/2] virtio-net: backport error handling bugfix Michael S. Tsirkin
2013-12-25 14:56 ` Michael S. Tsirkin [this message]
2013-12-25 18:33   ` [PATCH stable 1/2] virtio_net: fix error handling for mergeable buffers Michael Dalton
2013-12-25 19:19     ` Michael S. Tsirkin
2013-12-26  6:35       ` Michael Dalton
2013-12-26  7:28   ` Jason Wang
2013-12-25 14:56 ` [PATCH stable 2/2] virtio-net: make all RX paths handle erors consistently Michael S. Tsirkin
2013-12-26  7:28   ` Jason Wang
2013-12-26  7:31   ` Zhi Yong Wu
2013-12-25 20:13 ` [PATCH stable] virtio_net: don't leak memory or block when too many frags Michael S. Tsirkin
2013-12-26  6:35   ` Michael Dalton

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