[PATCH v4] ping: Check return value of function 'ping_queue_rcv_skb'

[PATCH v4] ping: Check return value of function 'ping_queue_rcv_skb'

[Zheng Yongjun]

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@huawei.com>
---
v2:
- use rc as return value to make code look cleaner
v3:
- delete unnecessary braces {}
v4:
- put variable 'rc' declaration at the beginning of function

 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..f01cde4fe08b 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -954,6 +954,7 @@ bool ping_rcv(struct sk_buff *skb)
 	struct sock *sk;
 	struct net *net = dev_net(skb->dev);
 	struct icmphdr *icmph = icmp_hdr(skb);
+	bool rc = false;
 
 	/* We assume the packet has already been checked by icmp_rcv */
 
@@ -968,14 +969,13 @@ 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))
+			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

Re: [PATCH v4] ping: Check return value of function 'ping_queue_rcv_skb'

[David Miller]

From: Zheng Yongjun <zhengyongjun3@huawei.com>
Date: Tue, 8 Jun 2021 14:42:46 +0800

> --- a/net/ipv4/ping.c
> +++ b/net/ipv4/ping.c
> @@ -954,6 +954,7 @@ bool ping_rcv(struct sk_buff *skb)
>  	struct sock *sk;
>  	struct net *net = dev_net(skb->dev);
>  	struct icmphdr *icmph = icmp_hdr(skb);
> +	bool rc = false;
>  
>  	/* We assume the packet has already been checked by icmp_rcv */
>  
> @@ -968,14 +969,13 @@ 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))
> +			rc = true;
>  		sock_put(sk);
> -		return true;
>  	}
>  	pr_debug("no socket, dropping\n");
>  
> -	return false;
> +	return rc;

YOu have chsanged the control flowe in a way that this pr_debug() can be inaccurate.
It can print when we did find a socket.

Please fix this.

Thank you.