Re: [PATCHv2] mac80211: fix NULL pointer dereference in ieee80211_compatible_rates

[Dan Williams <dcbw@redhat.com>]

On Sun, 2008-05-18 at 10:14 -0500, Larry Finger wrote:
> Dan Williams wrote:
> > On Sun, 2008-05-18 at 13:37 +0300, Tomas Winkler wrote:
> >> Again, mac should rather solve the problem that we do not connect to
> >> AP's that are not in the BSS list
> >> Personally I would NACK this as it's just hiding  the real problem
> > 
> > Ugh; is that what's happening?  If the AP isn't in the BSS list of the
> > card, then the card shouldn't be connecting to it.  It should have been
> > probe-scanned already and thus exist in the BSS list, right?
> > 
> > Dan
> > 
> >> The other issue is that we call ieee80211_rx_bss_put(dev, bss); before
> >> this call in ieee80211_send_assoc.
> 
> This AP certainly should have been in the BSS list. As I stated in the 
> original post, the system had been connected to that AP for about 18 hours 
> before the NULL bss NULL event occurred.
> 
> Clearly the sequence of events is improbable and it may be some time before 
> it happens again. What diagnostic information would be useful to capture 
> if/when it occurs? Is there any other location that I should monitor?

I'd think a printk whenever a unique BSS item is removed from the BSS
list; and the location of that removal in the code using __func__ and
__LINE__ in the output.

Dan