I've had a kernel panic in athrate-sample.c on line 353 compiled with
current sources.

I setup ath0 as an access point and bridge the traffic to Ethernet on a
NetBSD box. A laptop associates to it over wireless, and then I start
traffic through the NetBSD bridge (ping flood the laptop from a host on
the network).  When I walk far enough away from the access point with my
laptop, my connection is eventually lost. As soon as I come back close
enough for the laptop to reconnect I get the kernel panic.

This line:
KASSERT(ndx >= 0 && ndx < sn->num_rates, ("ndx is %d", ndx));
prints out: ndx is 0

Seems like it's been around for a while, I think the Atheros driver has
the same bug on Linux (it uses the same source code). They even have a
few patches attached to their problem report:
http://madwifi.org/ticket/162


Gilles Roy