Re: [dpdk-stable] [dpdk-dev] [PATCH] vhost: fix validate_msg_fds if VHOST_USER_VRING_NOFD_MASK set.

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Hi Zhike,

On 11/13/19 6:03 AM, Zhike Wang wrote:
> When VHOST_USER_VRING_NOFD_MASK is set, the fd_num is 0.
> 
> Fixes: bf47225 ("vhost: fix possible denial of service by leaking FDs")
> Signed-off-by: Zhike Wang <wangzk320@163.com>
> ---
>  lib/librte_vhost/vhost_user.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 90ecee1..0cfb8b7 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -1563,8 +1563,10 @@
>  	struct virtio_net *dev = *pdev;
>  	struct vhost_vring_file file;
>  	struct vhost_virtqueue *vq;
> +	int expected_fds;
>  
> -	if (validate_msg_fds(msg, 1) != 0)
> +	expected_fds = (msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK) ? 0 : 1;
> +	if (validate_msg_fds(msg, expected_fds) != 0)
>  		return RTE_VHOST_MSG_RESULT_ERR;
>  
>  	file.index = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
> @@ -1588,7 +1590,10 @@ static int vhost_user_set_vring_err(struct virtio_net **pdev __rte_unused,
>  			struct VhostUserMsg *msg,
>  			int main_fd __rte_unused)
>  {
> -	if (validate_msg_fds(msg, 1) != 0)
> +	int expected_fds;
> +
> +	expected_fds = (msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK) ? 0 : 1;
> +	if (validate_msg_fds(msg, expected_fds) != 0)
>  		return RTE_VHOST_MSG_RESULT_ERR;
>  
>  	if (!(msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK))
> @@ -1790,8 +1795,10 @@ static int vhost_user_set_vring_err(struct virtio_net **pdev __rte_unused,
>  	struct virtio_net *dev = *pdev;
>  	struct vhost_vring_file file;
>  	struct vhost_virtqueue *vq;
> +	int expected_fds;
>  
> -	if (validate_msg_fds(msg, 1) != 0)
> +	expected_fds = (msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK) ? 0 : 1;
> +	if (validate_msg_fds(msg, expected_fds) != 0)
>  		return RTE_VHOST_MSG_RESULT_ERR;
>  
>  	file.index = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
> 

Thanks for the fix, shame on me for missing that...

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Cc'ing stable also, as we'll need to backport it.

Regards,
Maxime