netdev - Re: mac80211 truesize bugs

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: <20080504021213.GA30660@gondor.apana.org.au>
Date:	Sun, 4 May 2008 10:12:13 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Johannes Berg <johannes@...solutions.net>
Cc:	David Miller <davem@...emloft.net>, mb@...sch.de,
	netdev@...r.kernel.org, linux-wireless@...r.kernel.org
Subject: Re: mac80211 truesize bugs

On Sun, May 04, 2008 at 04:08:36AM +0200, Johannes Berg wrote:
>
> So, what is mac80211 supposed to do? It needs up to 54 bytes of
> available headroom (for an encrypted mesh packet which currently can't
> really happen, but anyway) yet it cannot pskb_expand_head() either.
> Cloning each packet seems even more expensive, and just like skb_orphan
> subverts the purpose of the socket accounting.

If all/the majority of your packets need the space then put it in
LL_MAX_HEADER.  In any case, you should always expand the packet
if necessary in your output routine since LL_MAX_HEADER is just a
hint.  Yes cloning is expensive compared to not having to do it,
but as long as this is only done for the exception then it's
irrelevant.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
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