Re: [PATCH] cfg80211: Fix support for flushing old scan results

[Johannes Berg <johannes@sipsolutions.net>]

On Tue, 2018-05-22 at 16:50 +0200, Johannes Berg wrote:
> On Tue, 2018-05-22 at 09:48 -0500, Denis Kenzior wrote:
> > Hi Arend,
> > 
> > > > Are you saying the first result is from the Beacon and the other is from
> > > > the Probe Response?  Then why are the 'Information elements from Probe
> > > > Response frame' the way they are?
> > > 
> > > Nope. I am not saying that. I am saying that there are two probe 
> > > requests being sent. One with broadcast ssid, ie. ssid_len == 0, and 
> > > with ssid 'myssid'. But it is speculation without a sniffer capture.
> > 
> > Ah I see what you mean now.  No, we traced this down to hostapd itself 
> > and it was receiving a single Probe Request with the ssid set and 
> > replying to it per spec.  So I'm pretty confident this scenario isn't 
> > what is happening.  Let me try to get some actual packet captures...
> 
> Was "myssid" the real SSID, or did you hide that from us and it was
> really 9 characters long in the original?
> 
> If it was really 9 characters long I could imagine that there's a
> different bug with a beacon with all-zero-bytes having been received
> (and getting stuck into the probe response buffer for some reason), and
> then you *should* see both entries.

Or perhaps there's a bug with how we link the results between
hidden/non-hidden, but it seems to me that hostapd would never have
responded with a probe response with zeroed bytes.

johannes