netdev - Re: skb_checksum

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: <20120112141017.0a83e973@nehalam.linuxnetplumber.net>
Date:	Thu, 12 Jan 2012 14:10:17 -0800
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Ben Hutchings <bhutchings@...arflare.com>
Cc:	Herbert Xu <herbert@...dor.apana.org.au>,
	netdev <netdev@...r.kernel.org>,
	netfilter-devel <netfilter-devel@...r.kernel.org>
Subject: Re: skb_checksum_help() vs GSO

On Thu, 12 Jan 2012 20:42:10 +0000
Ben Hutchings <bhutchings@...arflare.com> wrote:

> skb_checksum_help() does:
> 
> 	if (unlikely(skb_shinfo(skb)->gso_size)) {
> 		/* Let GSO fix up the checksum. */
> 		goto out_set_summed;
> 	}
> ...
> out_set_summed:
> 	skb->ip_summed = CHECKSUM_NONE;
> out:
> 	return ret;
> 
> but skb_gso_segment() requires that skb->ip_summed == CHECKSUM_PARTIAL
> and WARNs if not.  I don't think there's any case where it's valid to
> call both.  Shouldn't skb_checksum_help() also WARN and return an error
> code instead of muddling on?
> 
> Inspecting the callers of skb_checksum_help(), it looks like sch_netem's
> 'corrupt' option and xt_CHECKSUM might trigger this case.
> 
> Ben.

Netem needs to check for GSO manually segment before calling skb_checksum_help.
I'll sort it out.
--
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