[ath9k-devel] [PATCH] ath9k: fix NULL-deref in hw_per_calibration() for ar9002

[Rajkumar Manoharan <rmanohar@qti.qualcomm.com>]

On Wed, May 07, 2014 at 09:22:58AM +0200, David Herrmann wrote:
> ah->caldata may be NULL if no channel is selected. Check for that before
> accessing it.
> 
> Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
> ---
> Hi
> 
> This is _definitely_ only a workaround, given that no-one guarantees ah->caldata
> is freed while we run in hw_per_calibration(). However, this patch fixes serious
> kernel panics with wifi-P2P on my machine.
> 
> I'm not sure why ah->caldata can be NULL, but it definitely is. I think the
> correct fix would be to synchronously stop any running hw-calibration before
> setting ah->caldata to NULL. I don't know whether/where that is done, so I wrote
> this small workaround.
>
David,

Whenever the DUT is moving to off-channel, ah->caldata is set to NULL in
hw_reset. As you mentioned, before doing hw_reset, the on-going calibration is stopped
synchronously. I using ar9280 for p2p (GO & CLI) validation. Somehow i do not observe
the panics. Is there a easiest way to reproduce the problem. Are you
using wireless-testing tree? Thanks for reporting the problem. Will try
to fix asap.

-Rajkumar