Re: [ 08/12] mac80211: zero initialize count field in ieee80211_tx_rate

[Willy Tarreau]

On Mon, Mar 12, 2012 at 01:57:52AM +0000, Ben Hutchings wrote:
> On Mon, 2012-03-12 at 01:20 +0100, Willy Tarreau wrote:
> > 2.6.32-longterm review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Mohammed Shafi Shajakhan <mohammed@xxxxxxxxxxxxxxxx>
> > 
> > commit 8617b093d0031837a7be9b32bc674580cfb5f6b5 upstream.
> > 
> > rate control algorithms concludes the rate as invalid
> > with rate[i].idx < -1 , while they do also check for rate[i].count is
> > non-zero. it would be safer to zero initialize the 'count' field.
> > recently we had a ath9k rate control crash where the ath9k rate control
> > in ath_tx_status assumed to check only for rate[i].count being non-zero
> > in one instance and ended up in using invalid rate index for
> > 'connection monitoring NULL func frames' which eventually lead to the crash.
> > thanks to Pavel Roskin for fixing it and finding the root cause.
> > https://bugzilla.redhat.com/show_bug.cgi?id=768639
> 
> In 2.6.32, ath_tx_status() checks that rates[i].idx >= 0, so it properly
> ignores these dummy entries.  Further, there is code further down the
> rate_control_get_rate() function that sets .idx only and appears to
> depend on the initialisation of .count = 1.
> 
> So I'm pretty sure this patch is wrong for 2.6.32; it could be
> backported but I don't think the change is necessary anyway.

Dropping it then, thanks Ben !

Willy

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