Re: [dpdk-stable] [PATCH 2/3] vhost: fix fd leak in dirty logging setup

["Xia, Chenbo" <chenbo.xia@intel.com>]

Hi Maxime,

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Thursday, November 5, 2020 7:46 PM
> To: dev@dpdk.org; Ding, Xuan <xuan.ding@intel.com>;
> stephen@networkplumber.org; Yigit, Ferruh <ferruh.yigit@intel.com>;
> thomas@monjalon.net; Xia, Chenbo <chenbo.xia@intel.com>
> Cc: stable@dpdk.org; Maxime Coquelin <maxime.coquelin@redhat.com>
> Subject: [PATCH 2/3] vhost: fix fd leak in dirty logging setup
> 
> This patch fixes a file descriptor leak which happens
> in the error path of vhost_user_set_log_base().
> 
> Fixes: 4796ad63ba1f ("examples/vhost: import userspace vhost application")
> Cc: stable@dpdk.org
> 
> Reported-by: Xuan Ding <xuan.ding@intel.com>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  lib/librte_vhost/vhost_user.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 473fd778ca..7dfda15991 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -2076,14 +2076,14 @@ vhost_user_set_log_base(struct virtio_net **pdev,
> struct VhostUserMsg *msg,
> 
>  	if (fd < 0) {
>  		VHOST_LOG_CONFIG(ERR, "invalid log fd: %d\n", fd);
> -		return RTE_VHOST_MSG_RESULT_ERR;
> +		goto close_msg_fds;

IMHO, there's nothing to close in this case. Before this check, validate_msg_fds
makes sure that this msg has only one fd and now this fd is invalid. So when this
error occurs, going to close_msg_fds always does nothing. So I think we don't need
this change here?

Thanks!
Chenbo

>  	}
> 
>  	if (msg->size != sizeof(VhostUserLog)) {
>  		VHOST_LOG_CONFIG(ERR,
>  			"invalid log base msg size: %"PRId32" != %d\n",
>  			msg->size, (int)sizeof(VhostUserLog));
> -		return RTE_VHOST_MSG_RESULT_ERR;
> +		goto close_msg_fds;
>  	}
> 
>  	size = msg->payload.log.mmap_size;
> @@ -2094,7 +2094,7 @@ vhost_user_set_log_base(struct virtio_net **pdev,
> struct VhostUserMsg *msg,
>  		VHOST_LOG_CONFIG(ERR,
>  			"log offset %#"PRIx64" and log size %#"PRIx64"
> overflow\n",
>  			off, size);
> -		return RTE_VHOST_MSG_RESULT_ERR;
> +		goto close_msg_fds;
>  	}
> 
>  	VHOST_LOG_CONFIG(INFO,
> @@ -2131,6 +2131,10 @@ vhost_user_set_log_base(struct virtio_net **pdev,
> struct VhostUserMsg *msg,
>  	msg->fd_num = 0;
> 
>  	return RTE_VHOST_MSG_RESULT_REPLY;
> +
> +close_msg_fds:
> +	close_msg_fds(msg);
> +	return RTE_VHOST_MSG_RESULT_ERR;
>  }
> 
>  static int vhost_user_set_log_fd(struct virtio_net **pdev __rte_unused,
> --
> 2.26.2