Re: [PATCH] cfg80211: validate scan channels

["Luis R. Rodriguez" <mcgrof@gmail.com>]

On Mon, Nov 2, 2009 at 4:32 AM, Johannes Berg <johannes@sipsolutions.net> wrote:
> Currently it is possible to request a scan on only
> disabled channels, which could be problematic for
> some drivers. Reject such scans, and also ignore
> disabled channels that are given. This resuls in
> the scan begin/end event only including channels
> that are actually used.
>
> This makes the mac80211 check for disabled channels
> superfluous. At the same time, remove the no-IBSS
> check from mac80211 -- nothing says that we should
> not find any networks on channels that cannot be
> used for an IBSS, even when operating in IBSS mode.
>
> Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

Side note that this patch reminds me of.

About two days ago I noticed that if my internal card enables channel
12 as its world roaming, I connect to my AP on channel 12 (therefore
lifting the passive scan flag), and if I then connect a USB device
which disables channel 12 communication will still go on on channel 12
on the old card but the channel will still have been marked as
disabled.

I figured I'd not here that we currently can trash these types of
connections because as noted with this patch we'd disable scanning --
but we only degrade the connection, we don't do something sensible. So
when we get a chance we should force a disconnect if a channel we're
using all of a sudden becomes disabled.

  Luis