Endless assoc/disassoc loop due to wpa_driver_nl80211_authenticate

Jouni Malinen j at w1.fi
Wed Nov 9 09:54:40 EST 2011


On Thu, Nov 03, 2011 at 09:55:51PM -0700, Ben Greear wrote:
> The wpa_driver_nl80211_authenticate method has some retry code
> that hits when the kernel returns -EALREADY:

> 		if (ret == -EALREADY && count == 1 && params->bssid &&
> 		    !params->local_state_change) {
> 			/*
> 			 * mac80211 does not currently accept new
> 			 * authentication if we are already authenticated. As a
> 			 * workaround, force deauthentication and try again.
> 			 */

> The problem is, that deauth call will cause a DEAUTH event shortly after,
> which will cause the station to deauth itself again.  This causes an endless loop of
> auth/deauth when you have lots of VIFS in non-WPA mode.

That DEAUTH event is supposed to get ignored..

> Any idea why this was put in to begin with?

That comment in the code above should explain the reason.. mac80211 (or
cfg80211; don't remember which) was (and for many parts, still is) quite
picky about the state in which some operations are run and the only way
wpa_supplicant could work around some connection issues was to
forcefully clear association and authentication state.

It could be possible to avoid these by making wpa_supplicant track the
authenticated state separately, but I'm not sure whether it is really
worth the extra complexity. Other approach could be to try to just
skip the authentication step based on EALREADY error and move to
association. That may have some other issues, though, so any change in
this area will require quite a bit of review and testing (including
testing with number of older kernel versions).

-- 
Jouni Malinen                                            PGP id EFC895FA


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