From: Jason Wang <jasowang@redhat.com>
Date: Wed, 2 May 2012 03:42:23 +0000 (+0800)
Subject: vhost_net: zerocopy: fix possible NULL pointer dereference of vq->bufs
X-Git-Tag: upstream/snapshot3+hdmi~7403^2~146^2~3
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c460f0573941cb28dc7f35595679c3508f0ce41f;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

vhost_net: zerocopy: fix possible NULL pointer dereference of vq->bufs

When we want to disable vhost_net backend while there's a tx work, a possible
NULL pointer defernece may happen we we try to deference the vq->bufs after
vhost_net_set_backend() assign a NULL to it.

As suggested by Michael, fix this by checking the vq->bufs instead of
vhost_sock_zcopy().

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

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 1f21d2a..35abe90 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -166,7 +166,7 @@ static void handle_tx(struct vhost_net *net)
 	if (wmem < sock->sk->sk_sndbuf / 2)
 		tx_poll_stop(net);
 	hdr_size = vq->vhost_hlen;
-	zcopy = vhost_sock_zcopy(sock);
+	zcopy = vq->ubufs;
 
 	for (;;) {
 		/* Release DMAs done buffers first */