linux-kernel - Re: softmac possible null deref [was: Complete report of Null dereference errors in kernel 2.6.17.1]

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Date:	Tue, 25 Jul 2006 08:20:44 +0200
From:	Johannes Weiner <hnazfoo@...glemail.com>
To:	linux-kernel@...r.kernel.org
Subject: Re: softmac possible null deref [was: Complete report of Null dereference errors in kernel 2.6.17.1]

Hi,

On Mon, Jul 24, 2006 at 05:00:08PM -0700, Thomas Dillig wrote:
> At least in 2.6.17.1, the function looks as follows:
> 
> /* Create an rts/cts frame */
> 445 static u32
> 446 ieee80211softmac_rts_cts(struct ieee80211_hdr_2addr **pkt,
> 447         struct ieee80211softmac_device *mac, struct ieee80211softmac_network *net,
> 448         u32 type)
> 449 {
> 450         /* Allocate Packet */
> 451         (*pkt) = kmalloc(IEEE80211_2ADDR_LEN, GFP_ATOMIC);     452         memset(*pkt, 0, IEEE80211_2ADDR_LEN); //*pkt is not checked for 
> NULL
> 453         if((*pkt) == NULL) //*pkt is checked for NULL
> 454                 return 0;
> 455         ieee80211softmac_hdr_2addr(mac, (*pkt), type, net->bssid);
> 456         return IEEE80211_2ADDR_LEN;
> 457 }

The function does not exist anymore in my 2.6.18-rc2-gabb5a5c tree.

> The report is just trying to say that "*pkt" is dereferenced inside the call to "memset" and checked for being null one line later.

This is really odd :) One should have used kzalloc() anyway.

Hannes
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