netdev - Re: [PATCH] GRE: Use IS_ERR_OR_NULL in gre_gso

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 linux-cve-announce 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]

Message-ID: <20130422021341.GG15680@verge.net.au>
Date:	Mon, 22 Apr 2013 11:13:41 +0900
From:	Simon Horman <horms@...ge.net.au>
To:	David Miller <davem@...emloft.net>
Cc:	eric.dumazet@...il.com, netdev@...r.kernel.org, xeb@...l.ru
Subject: Re: [PATCH] GRE: Use IS_ERR_OR_NULL in gre_gso_segment

On Sun, Apr 21, 2013 at 09:44:33PM -0400, David Miller wrote:
> From: Simon Horman <horms@...ge.net.au>
> Date: Mon, 22 Apr 2013 10:35:57 +0900
> 
> > On Fri, Apr 19, 2013 at 02:28:52PM -0400, David Miller wrote:
> >> From: Eric Dumazet <eric.dumazet@...il.com>
> >> Date: Fri, 19 Apr 2013 03:24:33 -0700
> >> 
> >> > On Fri, 2013-04-19 at 15:48 +0900, Simon Horman wrote:
> >> >> Signed-off-by: Simon Horman <horms@...ge.net.au>
> >> >> ---
> >> >>  net/ipv4/gre.c |    2 +-
> >> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >> >> 
> >> >> diff --git a/net/ipv4/gre.c b/net/ipv4/gre.c
> >> >> index d2d5a99..0ae998b 100644
> >> >> --- a/net/ipv4/gre.c
> >> >> +++ b/net/ipv4/gre.c
> >> >> @@ -168,7 +168,7 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
> >> >>  	/* segment inner packet. */
> >> >>  	enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
> >> >>  	segs = skb_mac_gso_segment(skb, enc_features);
> >> >> -	if (!segs || IS_ERR(segs))
> >> >> +	if (IS_ERR_OR_NULL(segs))
> >> >>  		goto out;
> >> >>  
> >> >>  	skb = segs;
> >> > 
> >> > Hi Simon
> >> > 
> >> > AFAIK I would change things so that NULL is not a possible value.
> >> > 
> >> > I don't really like IS_ERR_OR_NULL() because it hides some lazyness of
> >> > ours, and is more expensive (2 tests)
> >> > 
> >> > If we return NULL for an error, why not instead return -Esomething,
> >> > since caller is OK to get -ENOMEM,-Exxxxx,... ?
> >> 
> >> Sometimes IS_ERR_OR_NULL is appropriate, but not here, since the caller
> >> can more easily just provide good error codes all the time instead of
> >> sometimes returning nULL.
> > 
> > I am confused.
> > 
> > I'm not sure that my change actually alters the logic at all.
> > Is the suggestion that the logic should be changed somehow?
> 
> We're saying change skb_mac_gso_segment() to never return NULL, and
> always an error encoded pointer, rather than change the callers.

Thanks, I understand now.
--
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