mac80211: don't process work item with wrong frame

mac80211: don't process work item with wrong frame

When we process a frame, we currently just match it
to the work struct by the MAC addresses, and not by
the work type. This means that we can end up doing
the work for an association request item when (for
whatever reason) we receive another frame type, for
example a probe response. Processing the wrong type
of frame will lead to completely invalid data being
processed, and will lead to various problems like
thinking the association was successful even if the
AP never sent an assocation response.

Fix this by making each processing function check
that it is invoked for the right work struct type
only and continue processing otherwise (and drop
frames that we didn't expect).

This bug was uncovered during the debugging for
https://bugzilla.kernel.org/show_bug.cgi?id=15862
but doesn't seem to be the cause for any of the
various problems reported there.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>