patches/kernel/0014-vhost-fix-info-leak-due-to-uninitialized-memory.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: "Michael S. Tsirkin" <mst@redhat.com>
   3 Date: Thu, 16 Aug 2018 17:02:36 +0800
   4 Subject: [PATCH] vhost: fix info leak due to uninitialized memory
   5
   6 CVE-2018-1118
   7
   8 struct vhost_msg within struct vhost_msg_node is copied to userspace.
   9 Unfortunately it turns out on 64 bit systems vhost_msg has padding after
  10 type which gcc doesn't initialize, leaking 4 uninitialized bytes to
  11 userspace.
  12
  13 This padding also unfortunately means 32 bit users of this interface are
  14 broken on a 64 bit kernel which will need to be fixed separately.
  15
  16 Fixes: CVE-2018-1118
  17 Cc: stable@vger.kernel.org
  18 Reported-by: Kevin Easton <kevin@guarana.org>
  19 Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
  20 Reported-by: syzbot+87cfa083e727a224754b@syzkaller.appspotmail.com
  21 Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
  22 (cherry picked from commit 670ae9caaca467ea1bfd325cb2a5c98ba87f94ad)
  23 Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
  24 Acked-by: Khalid Elmously <khalid.elmously@canonical.com>
  25 Acked-by: Kamal Mostafa <kamal@canonical.com>
  26 Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
  27 Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
  28 ---
  29  drivers/vhost/vhost.c | 3 +++
  30  1 file changed, 3 insertions(+)
  31
  32 diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
  33 index 31bdfd296ced..a922d3d28a20 100644
  34 --- a/drivers/vhost/vhost.c
  35 +++ b/drivers/vhost/vhost.c
  36 @@ -2383,6 +2383,9 @@ struct vhost_msg_node *vhost_new_msg(struct vhost_virtqueue *vq, int type)
  37         struct vhost_msg_node *node = kmalloc(sizeof *node, GFP_KERNEL);
  38         if (!node)
  39                 return NULL;
  40 +
  41 +       /* Make sure all padding within the structure is initialized. */
  42 +       memset(&node->msg, 0, sizeof node->msg);
  43         node->vq = vq;
  44         node->msg.type = type;
  45         return node;