netdev - Re: [patch] ipv6: move dereference after check in fl

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Date:	Thu, 16 Aug 2012 16:11:36 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>, netdev@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [patch] ipv6: move dereference after check in fl_free()

Dan Carpenter <dan.carpenter@...cle.com> writes:

> There is a dereference before checking for NULL bug here.  Generally
> free() functions should accept NULL pointers.  For example, fl_create()
> can pass a NULL pointer to fl_free() on the error path.

Thanks.

Applied to user-namespace.git

Eric

>
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> ---
> Only needed on linux-next.
>
> diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
> index c836a6a..90bbefb 100644
> --- a/net/ipv6/ip6_flowlabel.c
> +++ b/net/ipv6/ip6_flowlabel.c
> @@ -91,12 +91,9 @@ static struct ip6_flowlabel *fl_lookup(struct net *net, __be32 label)
>  
>  static void fl_free(struct ip6_flowlabel *fl)
>  {
> -	switch (fl->share) {
> -	case IPV6_FL_S_PROCESS:
> -		put_pid(fl->owner.pid);
> -		break;
> -	}
>  	if (fl) {
> +		if (fl->share == IPV6_FL_S_PROCESS)
> +			put_pid(fl->owner.pid);
>  		release_net(fl->fl_net);
>  		kfree(fl->opt);
>  	}
--
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