[PATCH 4.14 122/159] virtio_net: fix return value check in receive_mergeable()

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Yunjian Wang <wangyunjian@xxxxxxxxxx>


[ Upstream commit 03e9f8a05bce7330bcd9c5cc54c8e42d0fcbf993 ]

The function virtqueue_get_buf_ctx() could return NULL, the return
value 'buf' need to be checked with NULL, not value 'ctx'.

Signed-off-by: Yunjian Wang <wangyunjian@xxxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/virtio_net.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -714,7 +714,7 @@ static struct sk_buff *receive_mergeable
 		int num_skb_frags;
 
 		buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx);
-		if (unlikely(!ctx)) {
+		if (unlikely(!buf)) {
 			pr_debug("%s: rx error: %d buffers out of %d missing\n",
 				 dev->name, num_buf,
 				 virtio16_to_cpu(vi->vdev,