linux-kernel - Re: [Stable-review] [104/145] netfilter: xt

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Message-ID: <20100313062446.GG12342@1wt.eu>
Date:	Sat, 13 Mar 2010 07:24:46 +0100
From:	Willy Tarreau <w@....eu>
To:	Greg KH <gregkh@...e.de>
Cc:	linux-kernel@...r.kernel.org, stable@...nel.org,
	Patrick McHardy <kaber@...sh.net>, akpm@...ux-foundation.org,
	Tim Gardner <tim.gardner@...onical.com>,
	torvalds@...ux-foundation.org, stable-review@...nel.org,
	alan@...rguk.ukuu.org.uk
Subject: Re: [Stable-review] [104/145] netfilter: xt_recent: fix false match

On Fri, Mar 12, 2010 at 04:27:17PM -0800, Greg KH wrote:
> 2.6.32-stable review patch.  If anyone has any objections, please let me know.
> 
> ----------------
> From: Tim Gardner <tim.gardner@...onical.com>
> 
> commit 8ccb92ad41cb311e52ad1b1fe77992c7f47a3b63 upstream.
> 
> A rule with a zero hit_count will always match.
> 
> Signed-off-by: Tim Gardner <tim.gardner@...onical.com>
> Signed-off-by: Patrick McHardy <kaber@...sh.net>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> 
> ---
>  net/netfilter/xt_recent.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/net/netfilter/xt_recent.c
> +++ b/net/netfilter/xt_recent.c
> @@ -260,7 +260,7 @@ recent_mt(const struct sk_buff *skb, con
>  		for (i = 0; i < e->nstamps; i++) {
>  			if (info->seconds && time_after(time, e->stamps[i]))
>  				continue;
> -			if (++hits >= info->hit_count) {
> +			if (info->hit_count && ++hits >= info->hit_count) {
>  				ret = !ret;
>  				break;
>  			}

I don't know if this has any undesired side effect or not, but the
logic is changed now since "hits" will not be increased anymore when
info->hit_count is zero. And the code does not make it obvious to me
what the intended purpose was.

For this reason I always find it dangerous to change variables in
if() conditions because it's where we change operations the most
frequently when fixing bugs.

Willy

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