From ee05d6939ed17b55e9c2466af32c208e0d547eb8 Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Tue, 14 Sep 2010 15:15:52 +0200
Subject: [PATCH] vhost-net: fix range checking in mrg bufs case
In mergeable buffer case, we use headcount, log_num
and seg as indexes in same-size arrays, and
we know that headcount <= seg and
log_num equals either 0 or seg.
Therefore, the right thing to do is range-check seg,
not headcount as we do now: these will be different
if guest chains s/g descriptors (this does not
happen now, but we can not trust the guest).
Long term, we should add BUG_ON checks to verify
two other indexes are what we think they should be.
Reported-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
drivers/vhost/net.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 29e850a7a2f98..7c8008225ee3a 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -243,7 +243,7 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
int r, nlogs = 0;
while (datalen > 0) {
- if (unlikely(headcount >= VHOST_NET_MAX_SG)) {
+ if (unlikely(seg >= VHOST_NET_MAX_SG)) {
r = -ENOBUFS;
goto err;
}