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Commit 670ae9ca authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

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: default avatarKevin Easton <kevin@guarana.org>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reported-by: default avatar <syzbot+87cfa083e727a224754b@syzkaller.appspotmail.com>
Signed-off-by: default avatarMichael 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;