linux-kernel - rtlwifi/rtl8192cu AP mode broken with PS STA

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <e2924d81-0e30-2dd0-292b-428fea199484@maciej.szmigiero.name>
Date:   Mon, 29 Mar 2021 00:54:28 +0200
From:   "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
To:     Ping-Ke Shih <pkshih@...ltek.com>,
        Kalle Valo <kvalo@...eaurora.org>
Cc:     Johannes Berg <johannes@...solutions.net>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: rtlwifi/rtl8192cu AP mode broken with PS STA

Hi,

It looks like rtlwifi/rtl8192cu AP mode is broken when a STA is using PS,
since the driver does not update its beacon to account for TIM changes,
so a station that is sleeping will never learn that it has packets
buffered at the AP.

Looking at the code, the rtl8192cu driver implements neither the set_tim()
callback, nor does it explicitly update beacon data periodically, so it
has no way to learn that it had changed.

This results in the AP mode being virtually unusable with STAs that do
PS and don't allow for it to be disabled (IoT devices, mobile phones,
etc.).

I think the easiest fix here would be to implement set_tim() for example
the way rt2x00 driver does: queue a work or schedule a tasklet to update
the beacon data on the device.

Thanks,
Maciej