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Subject[PATCH 5/6] vhost_net: fix use after free of vq->ubufs
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When zerocopy socket is used, ubufs pointer were used in handle_tx()
without any validation. This would cause NULL pointer deference after
it has been freed in vhost_net_set_backend(). Fix this by check the
pointer before using it.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/vhost/net.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f0da2c3..29abd65 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -163,10 +163,15 @@ static void handle_tx(struct vhost_net *net)
mutex_lock(&vq->mutex);
vhost_disable_notify(&net->dev, vq);

+ zcopy = vhost_sock_zcopy(sock);
+ if (zcopy && !vq->ubufs) {
+ mutex_unlock(&vq->mutex);
+ return;
+ }
+
if (wmem < sock->sk->sk_sndbuf / 2)
tx_poll_stop(net);
hdr_size = vq->vhost_hlen;
- zcopy = vhost_sock_zcopy(sock);

for (;;) {
/* Release DMAs done buffers first */


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