Kernel panic in ieee80211_calculate_rx_timestamp

I recently got a ath9k_htc based dongle and running kismet for a few hours results in a kernel panic (divide error) in ieee80211_calculate_rx_timestamp with kernel 3.11.0.

The problem seems to occur when the call to cfg80211_calculate_bitrate returns 0. I've used this patch to temporarily works around the problem.

index 2265445..037b737 100644
@@ -2156,6 +2156,9 @@ u64 ieee80211_calculate_rx_timestamp(struct

ieee80211_local *local,

        rate = cfg80211_calculate_bitrate(&ri);

+ if (WARN_ON(!rate))
+ return 0;
+

        /* rewind from end of MPDU */
        if (status->flag & RX_FLAG_MACTIME_END)
                ts -= mpdu_len * 8 * 10 / rate;

http://i.imgur.com/BrpaCgI.jpg here is the output of the panic.

/Thomas Lindroth

Seems fair, but maybe it should print out the rate info so you can see what was actually received - most likely this is a driver bug though.

If you submit a patch that can be applied with signed-off-by etc. I can apply it.

johannes

Sorry for the late reply. My first post was mostly meant as a bug report. I don't have the insight needed for a proper fix but that patch should point a developer in the right direction.

/Thomas Lindroth