Re: [PATCH] netfilter: nfnetlink_queue: Fix redundant comparison of unsigned value

[Pablo Neira Ayuso <pablo@netfilter.org>]

Hi,

On Mon, Dec 09, 2024 at 09:49:18PM +0100, Karol Przybylski wrote:
> The comparison seclen >= 0 in net/netfilter/nfnetlink_queue.c is redundant because seclen is an unsigned value, and such comparisons are always true.
>
> This patch removes the unnecessary comparison replacing it with just 'greater than'
> 
> Discovered in coverity, CID 1602243
> 
> Signed-off-by: Karol Przybylski <karprzy7@gmail.com>
> ---
>  net/netfilter/nfnetlink_queue.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
> index 5110f29b2..eacb34ffb 100644
> --- a/net/netfilter/nfnetlink_queue.c
> +++ b/net/netfilter/nfnetlink_queue.c
> @@ -643,7 +643,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
>  
>  	if ((queue->flags & NFQA_CFG_F_SECCTX) && entskb->sk) {
>  		seclen = nfqnl_get_sk_secctx(entskb, &ctx);
> -		if (seclen >= 0)
> +		if (seclen > 0)

What tree are you using? I don't see this code in net-next.git

>  			size += nla_total_size(seclen);
>  	}
>  
> @@ -810,7 +810,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
>  	}
>  
>  	nlh->nlmsg_len = skb->len;
> -	if (seclen >= 0)
> +	if (seclen > 0)
>  		security_release_secctx(&ctx);
>  	return skb;
>  
> @@ -819,7 +819,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
>  	kfree_skb(skb);
>  	net_err_ratelimited("nf_queue: error creating packet message\n");
>  nlmsg_failure:
> -	if (seclen >= 0)
> +	if (seclen > 0)
>  		security_release_secctx(&ctx);
>  	return NULL;
>  }
> -- 
> 2.34.1
>