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

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Message-ID: <1c31a9fa-6322-cebb-c78c-189c905eaf86@gmail.com>
Date:   Mon, 7 Jun 2021 10:26:15 -0600
From:   David Ahern <dsahern@...il.com>
To:     Zheng Yongjun <zhengyongjun3@...wei.com>, 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] ping: Check return value of function 'ping_queue_rcv_skb'

On 6/7/21 3:10 AM, 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>
> ---
>  net/ipv4/ping.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
> index 1c9f71a37258..8e84cde95011 100644
> --- a/net/ipv4/ping.c
> +++ b/net/ipv4/ping.c
> @@ -968,10 +968,11 @@ bool ping_rcv(struct sk_buff *skb)
>  		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)) {
> +			sock_put(sk);
> +			return true;
> +		}
>  		sock_put(sk);
> -		return true;
>  	}
>  	pr_debug("no socket, dropping\n");
>  
> 

declare a default return variable:

	bool rc = false;

set to to true if ping_queue_rcv_skb() fails and have one exit path with
one sock_put.