Re: [PATCH] ALSA: hda: fix NULL pointer dereference during suspend

[Ranjani Sridharan <ranjani.sridharan@linux.intel.com>]

On Thu, 2020-07-30 at 15:07 +0200, Takashi Iwai wrote:
> On Wed, 29 Jul 2020 18:06:25 +0200,
> Takashi Iwai wrote:
> > On Wed, 29 Jul 2020 17:03:22 +0200,
> > Ranjani Sridharan wrote:
> > > On Wed, 2020-07-29 at 09:48 +0200, Takashi Iwai wrote:
> > > > On Wed, 29 Jul 2020 01:10:11 +0200,
> > > > Ranjani Sridharan wrote:
> > > > > When the ASoC card registration fails and the codec component
> > > > > driver
> > > > > never probes, the codec device is not initialized and
> > > > > therefore
> > > > > memory for codec->wcaps is not allocated. This results in a
> > > > > NULL
> > > > > pointer
> > > > > dereference when the codec driver suspend callback is invoked
> > > > > during
> > > > > system suspend. Fix this by returning without performing any
> > > > > actions
> > > > > during codec suspend/resume if the card was not registered
> > > > > successfully.
> > > > > 
> > > > > Reviewed-by: Pierre-Louis Bossart <
> > > > > pierre-louis.bossart@linux.intel.com>
> > > > > Signed-off-by: Ranjani Sridharan <
> > > > > ranjani.sridharan@linux.intel.com
> > > > 
> > > > The code changes look OK to apply, but I still wonder how the
> > > > runtime
> > > > PM gets invoked even if the device is not instantiated
> > > > properly?
> > > Hi Takashi,
> > > 
> > > Its not runtime PM suspend but rather the system PM suspend
> > > callback
> > > that is invoked when the system is suspended that ends up
> > > callling the
> > > the runtime PM callback. So, the sequence is:
> > > hda_codec_pm_suspend()
> > >    -> pm_runtime_force_suspend()
> > >           -> hda_codec_runtime_suspend()
> > 
> > OK, but the problem is still same.  The basic problem is that the
> > hda_codec_driver_probe() is called for the hda_codec object that
> > hasn't been initialized and bypasses to ext_ops.hdev_attach.
> > 
> > So, we can factor out the fundamental part of
> > snd_hda_codec_device_new() that is irrelevant with the card object
> > and
> > call it in hdac_hda_dev_probe().
> 
> I meant something like below (totally untested)
Thanks, Takashi. I can test this out and get back to you by next week.

Thanks,
Ranjani