From: Michael S. Tsirkin Date: Fri, 11 May 2018 21:33:10 +0000 (+0300) Subject: vhost: fix info leak due to uninitialized memory X-Git-Tag: v4.18-rc1~13^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=670ae9caaca467ea1bfd325cb2a5c98ba87f94ad;p=thirdparty%2Fkernel%2Flinux.git 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 Signed-off-by: Michael S. Tsirkin Reported-by: syzbot+87cfa083e727a224754b@syzkaller.appspotmail.com Signed-off-by: Michael S. Tsirkin --- diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index f0be5f35ab28f..9beefa6ed1ce0 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -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;