linux-kernel - Re: [PATCH v3] ping: Check return value of function 'ping_queue_rcv

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Date:   Tue, 8 Jun 2021 09:08:26 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Zheng Yongjun <zhengyongjun3@...wei.com>
Cc:     davem@...emloft.net, yoshfuji@...ux-ipv6.org, dsahern@...nel.org,
        kuba@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] ping: Check return value of function
 'ping_queue_rcv_skb'

On Tue, Jun 08, 2021 at 10:08:53AM +0800, Zheng Yongjun wrote:
> Function 'ping_queue_rcv_skb' not always return success, which will
> also return fail. If not check the wrong return value of it, lead
> to function `ping_rcv` return success.
> 
> Signed-off-by: Zheng Yongjun <zhengyongjun3@...wei.com>
> ---
> v2:
> - use rc as return value to make code look cleaner
> v3:
> - delete unnecessary braces {}
>  net/ipv4/ping.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
> index 1c9f71a37258..af9da2f7dc85 100644
> --- a/net/ipv4/ping.c
> +++ b/net/ipv4/ping.c
> @@ -963,19 +963,19 @@ bool ping_rcv(struct sk_buff *skb)
>  	/* Push ICMP header back */
>  	skb_push(skb, skb->data - (u8 *)icmph);
>  
> +	bool rc = false;

Declaration of new variables in the middle of function is C++, while the
kernel is written in C. Please put variable declaration at the beginning
of function.

Thanks

>  	sk = ping_lookup(net, skb, ntohs(icmph->un.echo.id));
>  	if (sk) {
>  		struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
>  
>  		pr_debug("rcv on socket %p\n", sk);
> -		if (skb2)
> -			ping_queue_rcv_skb(sk, skb2);
> +		if (skb2 && !ping_queue_rcv_skb(sk, skb2))
> +			rc = true;
>  		sock_put(sk);
> -		return true;
>  	}
>  	pr_debug("no socket, dropping\n");
>  
> -	return false;
> +	return rc;
>  }
>  EXPORT_SYMBOL_GPL(ping_rcv);
>  
> -- 
> 2.25.1
>