From: Jason Wang <jasowang@redhat.com>
Date: Tue, 30 Oct 2018 06:10:49 +0000 (+0800)
Subject: vhost: Fix Spectre V1 vulnerability
X-Git-Tag: v4.18.17~31
X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c75d697c8197364323d29e33698a38ab8152d218;p=linux

vhost: Fix Spectre V1 vulnerability

[ 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>
---

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 560ed8711706..c4424cbd9943 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -30,6 +30,7 @@
 #include <linux/sched/mm.h>
 #include <linux/sched/signal.h>
 #include <linux/interval_tree_generic.h>
+#include <linux/nospec.h>
 
 #include "vhost.h"
 
@@ -1362,6 +1363,7 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
 	if (idx >= d->nvqs)
 		return -ENOBUFS;
 
+	idx = array_index_nospec(idx, d->nvqs);
 	vq = d->vqs[idx];
 
 	mutex_lock(&vq->mutex);