linux-kernel - Re: [PATCH] wireless: wext: allocate space for NULL-termination for 32byte SSIDs

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Message-ID: <1260873307.3692.10.camel@johannes.local>
Date:	Tue, 15 Dec 2009 11:35:07 +0100
From:	Johannes Berg <johannes@...solutions.net>
To:	Holger Schurig <holgerschurig@...il.com>
Cc:	linux-wireless@...r.kernel.org, David Miller <davem@...emloft.net>,
	daniel@...aq.de, linux-kernel@...r.kernel.org, dcbw@...hat.com,
	m.hirsch@...mfeld.com, netdev@...r.kernel.org,
	libertas-dev@...ts.infradead.org, stable@...nel.org
Subject: Re: [PATCH] wireless: wext: allocate space for NULL-termination
 for 32byte SSIDs

On Tue, 2009-12-15 at 11:30 +0100, Holger Schurig wrote:
> > drivers/net/wireless/libertas$ grep lbs_deb_ * | grep ssid
> > |grep '%s' 
> > assoc.c:	lbs_deb_join("current SSID '%s', ssid length %u\n",
> > assoc.c:	lbs_deb_join("requested ssid '%s', ssid length %u\n",
> > assoc.c:	lbs_deb_join("ADHOC_START: SSID '%s', ssid
> >               length %u\n", 
> > scan.c:		lbs_deb_wext("set_scan, essid '%s'\n",
> 
> All those lines are gone once my cfg80211 lands.
> 
> Do you know any way to make sparse moan about them?

Sorry, no, I don't think that's even possible unless you play dirty with
tricks like __iomem uses for instance but that'd require a lot of
casting in otherwise valid uses.

> BTW: the libertas firmware sometimes treat an SSID as a 
> zero-terminated string. There are some firmware commands that 
> accept just an u8[32] bytes for the SSID, but not an ssid_len, 
> e.g. in the CMD_802_11_AD_HOC_START command.
> 
> You therefore can't connect to the otherwise legitimate SSID of 
> TEST\0\0\0.

Ick! I guess your cfg80211 IBSS join handler needs to check for that
then and refuse such an SSID.

johannes


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