Commit ee05d693 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin

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: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 053d8f66
...@@ -243,7 +243,7 @@ static int get_rx_bufs(struct vhost_virtqueue *vq, ...@@ -243,7 +243,7 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
int r, nlogs = 0; int r, nlogs = 0;
while (datalen > 0) { while (datalen > 0) {
if (unlikely(headcount >= VHOST_NET_MAX_SG)) { if (unlikely(seg >= VHOST_NET_MAX_SG)) {
r = -ENOBUFS; r = -ENOBUFS;
goto err; goto err;
} }
......
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