debian/patches/extra/CVE-2016-7422-virtio-add-check-for-descriptor-s-mapped-address.patch

   1 From 1723b5e7962eb077353bab0772ca8114774b6c60 Mon Sep 17 00:00:00 2001
   2 From: Prasad J Pandit <pjp@fedoraproject.org>
   3 Date: Mon, 19 Sep 2016 23:55:45 +0530
   4 Subject: [PATCH 4/7] virtio: add check for descriptor's mapped address
   5
   6 virtio back end uses set of buffers to facilitate I/O operations.
   7 If its size is too large, 'cpu_physical_memory_map' could return
   8 a null address. This would result in a null dereference while
   9 un-mapping descriptors. Add check to avoid it.
  10
  11 Reported-by: Qinghao Tang <luodalongde@gmail.com>
  12 Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
  13 Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
  14 Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
  15 Reviewed-by: Laszlo Ersek <lersek@redhat.com>
  16 ---
  17  hw/virtio/virtio.c | 5 +++++
  18  1 file changed, 5 insertions(+)
  19
  20 diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
  21 index 74c085c..eabe573 100644
  22 --- a/hw/virtio/virtio.c
  23 +++ b/hw/virtio/virtio.c
  24 @@ -473,6 +473,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove
  25          }
  26
  27          iov[num_sg].iov_base = cpu_physical_memory_map(pa, &len, is_write);
  28 +        if (!iov[num_sg].iov_base) {
  29 +            error_report("virtio: bogus descriptor or out of resources");
  30 +            exit(1);
  31 +        }
  32 +
  33          iov[num_sg].iov_len = len;
  34          addr[num_sg] = pa;
  35
  36 --
  37 2.1.4
  38