netdev - Re: [PATCH 3/3] tap: free skb if flags error

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Date:   Fri, 1 Dec 2017 15:10:08 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     wexu@...hat.com, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     mst@...hat.com, mjrosato@...ux.vnet.ibm.com
Subject: Re: [PATCH 3/3] tap: free skb if flags error



On 2017年12月01日 13:54, wexu@...hat.com wrote:
> From: Wei Xu <wexu@...hat.com>
>
> tap_recvmsg() supports accepting skb by msg_control after
> commit 3b4ba04acca8 ("tap: support receiving skb from msg_control"),
> the skb if presented should be freed within the function, otherwise
> it would be leaked.
>
> Signed-off-by: Wei Xu <wexu@...hat.com>
> Reported-by: Matthew Rosato <mjrosato@...ux.vnet.ibm.com>
> ---
>   drivers/net/tap.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/tap.c b/drivers/net/tap.c
> index e9489b8..1c66b75 100644
> --- a/drivers/net/tap.c
> +++ b/drivers/net/tap.c
> @@ -1154,9 +1154,13 @@ static int tap_recvmsg(struct socket *sock, struct msghdr *m,
>   		       size_t total_len, int flags)
>   {
>   	struct tap_queue *q = container_of(sock, struct tap_queue, sock);
> +	struct sk_buff *skb = m->msg_control;
>   	int ret;
> -	if (flags & ~(MSG_DONTWAIT|MSG_TRUNC))
> +	if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) {
> +		if (skb)
> +			kfree_skb(skb);
>   		return -EINVAL;
> +	}
>   	ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT,
>   			  m->msg_control);

Need to deal with iov_iterator_count() == 0.

Thanks

>   	if (ret > total_len) {