Crash in mac80211 when connecting to WPA2-encrypted AP with Intel WL 5300

[alm]

After upgrading to linux-image-2.6.27-8-generic and linux-backports-modules-2.6.27-8-generic from proposed-updates, my laptop fails to associate with an WPA2 encrypted AP. It works if I disable wireless security (no WPA or WEP). The cause is probably a module crash in mac80211 (see attached dmesg).

It works fine if I remove linux-backports-modules (it uses the modules included in linux-image-2.6.27-8-generic). It works fine with linux-image-2.6.27-7-generic + linux-backport-modules-2.6.27-7-generic.