Commit 670ae9ca authored May 12, 2018 by Michael S. Tsirkin

vhost: fix info leak due to uninitialized memory



struct vhost_msg within struct vhost_msg_node is copied to userspace.
Unfortunately it turns out on 64 bit systems vhost_msg has padding after
type which gcc doesn't initialize, leaking 4 uninitialized bytes to
userspace.

This padding also unfortunately means 32 bit users of this interface are
broken on a 64 bit kernel which will need to be fixed separately.

Fixes: CVE-2018-1118
Cc: stable@vger.kernel.org
Reported-by: Kevin Easton <kevin@guarana.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reported-by:  <syzbot+87cfa083e727a224754b@syzkaller.appspotmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

parent 55e49dc4

drivers/vhost/vhost.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -2345,6 +2345,9 @@ struct vhost_msg_node vhost_new_msg(struct vhost_virtqueue vq, int type)
		struct vhost_msg_node node = kmalloc(sizeof node, GFP_KERNEL);
		if (!node)
		return NULL;

		/* Make sure all padding within the structure is initialized. */
		memset(&node->msg, 0, sizeof node->msg);
		node->vq = vq;
		node->msg.type = type;
		return node;

Admin message