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vhost: fix info leak due to uninitialized memory

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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@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael S. Tsirkin 2018-05-12 00:33:10 +03:00 committed by Greg Kroah-Hartman
parent a875bc1c9e
commit 9681c3bdb0
1 changed files with 3 additions and 0 deletions
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3
drivers/vhost/vhost.c
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@ -2295,6 +2295,9 @@ 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;