linux-kernel - Re: [PATCH 2/3] netfilter: potential null derefence.

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Message-ID: <20120302012208.GA10185@1984>
Date:	Fri, 2 Mar 2012 02:22:08 +0100
From:	Pablo Neira Ayuso <pablo@...filter.org>
To:	santosh nayak <santoshprasadnayak@...il.com>
Cc:	bart.de.schuymer@...dora.be, kaber@...sh.net,
	shemminger@...tta.com, davem@...emloft.net,
	netfilter-devel@...r.kernel.org, netfilter@...r.kernel.org,
	coreteam@...filter.org, bridge@...ts.linux-foundation.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 2/3] netfilter: potential null derefence.

On Thu, Mar 01, 2012 at 02:47:14PM +0530, santosh nayak wrote:
> From: Santosh Nayak <santoshprasadnayak@...il.com>
> 
> I am getting following error.
> " net/bridge/netfilter/ebtables.c:269 ebt_do_table()
>   error: potential null derefence 'cs'"
> 
>     i = cs[sp].n;  // If cs == Null then this will cause problem.
> 
> Signed-off-by: Santosh Nayak <santoshprasadnayak@...il.com>
> ---
>  net/bridge/netfilter/ebtables.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
> 
> diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
> index f3fcbd9..9c0f177 100644
> --- a/net/bridge/netfilter/ebtables.c
> +++ b/net/bridge/netfilter/ebtables.c
> @@ -209,8 +209,10 @@ unsigned int ebt_do_table (unsigned int hook, struct sk_buff *skb,
>  	   smp_processor_id());
>  	if (private->chainstack)
>  		cs = private->chainstack[smp_processor_id()];
> -	else
> +	else {
>  		cs = NULL;

I just noticed we can remove this cs = NULL. No need to resend, I'll
mangle it myself.

> +		goto out;
> +	}
>  	chaininfo = private->hook_entry[hook];
>  	nentries = private->hook_entry[hook]->nentries;
>  	point = (struct ebt_entry *)(private->hook_entry[hook]->data);
> @@ -313,6 +315,7 @@ letscontinue:
>  		read_unlock_bh(&table->lock);
>  		return NF_ACCEPT;
>  	}
> +out:
>  	read_unlock_bh(&table->lock);
>  	return NF_DROP;
>  }
> -- 
> 1.7.4.4
> 
> --
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