From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 16 Aug 2018 17:02:36 +0800 Subject: [PATCH] vhost: fix info leak due to uninitialized memory CVE-2018-1118 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 (cherry picked from commit 670ae9caaca467ea1bfd325cb2a5c98ba87f94ad) Signed-off-by: Po-Hsu Lin Acked-by: Khalid Elmously Acked-by: Kamal Mostafa Signed-off-by: Khalid Elmously Signed-off-by: Stoiko Ivanov --- drivers/vhost/vhost.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 31bdfd296ced..a922d3d28a20 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -2383,6 +2383,9 @@ 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;