netdev - Re: [PATCH RFC v3 net 1/2] ipv6: Remove the net->ipv6.ip6_null

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 08 Oct 2014 15:08:38 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	kafai@...com
Cc:	netdev@...r.kernel.org, hannes@...essinduktion.org
Subject: Re: [PATCH RFC v3 net 1/2] ipv6: Remove the
 net->ipv6.ip6_null_entry check

From: Martin KaFai Lau <kafai@...com>
Date: Mon, 6 Oct 2014 17:05:14 -0700

> The above BACKTRACK have already caught the rt == net->ipv6.ip6_null_entry case
> 
> Cc: Hannes Frederic Sowa <hannes@...essinduktion.org>
> Signed-off-by: Martin KaFai Lau <kafai@...com>
 ...
> @@ -936,8 +936,7 @@ restart:
>  	if (rt->rt6i_nsiblings)
>  		rt = rt6_multipath_select(rt, fl6, oif, strict | reachable);
>  	BACKTRACK(net, &fl6->saddr);
> -	if (rt == net->ipv6.ip6_null_entry ||
> -	    rt->rt6i_flags & RTF_CACHE)
> +	if (rt->rt6i_flags & RTF_CACHE)
>  		goto out;
>  
>  	dst_hold(&rt->dst);

I think this is sort of going in the wrong direction.

The BACKTRACK() macro hides a lot of side effects inside of it's
implementation, and worst of all it hides a change of control flow
with it's "goto out;" and "goto restart;"

I'd rather see us clean this up in some way that someone auditing this
code won't be tricked into missing the control flow side effects, than
adding more dependencies upon BACKTRACK()'s implementation.

Thanks.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html