[PATCH 4.4 099/114] vhost: Fix Spectre V1 vulnerability

Greg Kroah-Hartman
2018-11-09T07:38:27Z

From: Jason Wang <jasowang@redhat.com>

[ Upstream commit ff002269a4ee9c769dbf9365acef633ebcbd6cbe ]

The idx in vhost_vring_ioctl() was controlled by userspace, hence a
potential exploitation of the Spectre variant 1 vulnerability.

Fixing this by sanitizing idx before using it to index d->vqs.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/vhost/vhost.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -27,6 +27,7 @@
#include <linux/cgroup.h>
#include <linux/module.h>
#include <linux/sort.h>
+#include <linux/nospec.h>

#include "vhost.h"

@@ -748,6 +749,7 @@ long vhost_vring_ioctl(struct vhost_dev
if (idx >= d->nvqs)
return -ENOBUFS;

+ idx = array_index_nospec(idx, d->nvqs);
vq = d->vqs[idx];

mutex_lock(&vq->mutex);