wireless: regulatory: fix channel disabling race condition
authorJohannes Berg <johannes.berg@intel.com>
Tue, 16 Apr 2013 12:32:26 +0000 (14:32 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 8 May 2013 02:57:27 +0000 (19:57 -0700)
commitd2a51f02ccc6fac30f8cdb7e5f2791b2fe43d129
tree629b25263b78ed748b92ff20abb596e0d9566be1
parentcfb0a900641f0d5c84bc1e68bbf3e312ae37c549
wireless: regulatory: fix channel disabling race condition

commit 990de49f74e772b6db5208457b7aa712a5f4db86 upstream.

When a full scan 2.4 and 5 GHz scan is scheduled, but then the 2.4 GHz
part of the scan disables a 5.2 GHz channel due to, e.g. receiving
country or frequency information, that 5.2 GHz channel might already
be in the list of channels to scan next. Then, when the driver checks
if it should do a passive scan, that will return false and attempt an
active scan. This is not only wrong but can also lead to the iwlwifi
device firmware crashing since it checks regulatory as well.

Fix this by not setting the channel flags to just disabled but rather
OR'ing in the disabled flag. That way, even if the race happens, the
channel will be scanned passively which is still (mostly) correct.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net/wireless/reg.c