[PATCH] mesh: Fix mesh SAE auth on low spec devices

Jouni Malinen j at w1.fi
Sun Aug 2 14:53:02 EDT 2015


On Wed, Jul 08, 2015 at 10:41:36PM +0900, Masashi Honma wrote:
> The mesh SAE auth often fails with master branch. By bisect I found
> commit eb5fee0bf50444419ac12d3c7f38f27a47523a47 causes this issue. This does not
> mean the commit has a bug. This is just a CPU resource issue.
> 
> After the commit, sae_derive_pwe_ecc() spends 101(msec) on my PC (Intel Atom
> N270 1.6GHz). But dot11RSNASAERetransPeriod is 40(msec). So
> auth_sae_retransmit_timer() is always called and it can causes continuous frame
> exchanges. Before the commit, it was 23(msec).
> 
> On the IEEE 802.11 spec, the default value of dot11RSNASAERetransPeriod is
> defined as 40(msec). But it looks short because generally mesh functionality
> will be used on low spec devices. Indeed Raspberry Pi B+
> (ARM ARM1176JZF-S 700MHz) requires 287(msec) for new sae_derive_pwe_ecc().
> 
> So this patch makes the default to 1000(msec) and it configurable.
> 
> This issue does not occur on infrastructure SAE because the
> dot11RSNASAERetransPeriod is not used on it.

Thanks, applied.

-- 
Jouni Malinen                                            PGP id EFC895FA


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