4.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael S. Tsirkin <mst@xxxxxxxxxx> commit 670ae9caaca467ea1bfd325cb2a5c98ba87f94ad upstream. 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@xxxxxxxxxxxxxxx Reported-by: Kevin Easton <kevin@xxxxxxxxxxx> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Reported-by: syzbot+87cfa083e727a224754b@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/vhost/vhost.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -2345,6 +2345,9 @@ struct vhost_msg_node *vhost_new_msg(str 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;
