On 09/19/16 20:25, P J P wrote:
> From: Prasad J Pandit
>
> virtio back end uses set of buffers to facilitate I/O operations.
> If its size is too large, 'cpu_physical_memory_map' could return
> a null address. This would result in a null dereference while
> un-mapping descriptors. Add check to avoid it.
>
> Reported-by: Qinghao Tang
> Signed-off-by: Prasad J Pandit
> ---
> hw/virtio/virtio.c | 5 +
> 1 file changed, 5 insertions(+)
>
> Update per:
> -> https://lists.gnu.org/archive/html/qemu-devel/2016-09/msg04329.html
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 15ee3a7..a4ebf8c 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -472,6 +472,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg,
> hwaddr *addr, struct iove
> }
>
> iov[num_sg].iov_base = cpu_physical_memory_map(pa, &len, is_write);
> +if (!iov[num_sg].iov_base) {
> +error_report("virtio: bogus descriptor or out of resources");
> +exit(1);
> +}
> +
> iov[num_sg].iov_len = len;
> addr[num_sg] = pa;
>
>
Reviewed-by: Laszlo Ersek
