issue with BSS_FLUSH - cache not cleaned

Jouni Malinen j at
Sun Jan 14 09:51:40 PST 2024

On Tue, Jan 09, 2024 at 05:32:26PM +0100, Antonio Prcela wrote:
> The results of the first scan are still available when scanning for all networks
> and within 10 seconds scanning again but for specific frequencie(s).
> Even if 'BSS_FLUSH' used in between. See exaple:

BSS_FLUSH does not clear the scan results that are maintained in the
driver (or cfg80211 with many Linux drivers) and as such, the following
scan operation will likely result in restoring all BSS entries back into

> > SCAN only_new=1 freq=2462

In theory, that might drop some of the results on other channels, but it
might need a couple of attempts with "SCAN only_new=1 freq=<freq of an
empty channel>" (followed by yet another BSS_FLUSH) to get to a point
where BSS entries are not coming back. It should also be noted that
channel a specific channel on the 2.4 GHz is actually able to receive
frames from neighboring channels and as such, that might result in some
"unexpected" results showing up as well.

Jouni Malinen                                            PGP id EFC895FA

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