From: Takashi Iwai <tiwai@suse.de>
To: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Cc: yong.zhi@intel.com, alsa-devel@alsa-project.org,
broonie@kernel.org,
Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
tiwai@suse.com
Subject: Re: [PATCH] ALSA: hda: fix NULL pointer dereference during suspend
Date: Wed, 29 Jul 2020 18:06:25 +0200 [thread overview]
Message-ID: <s5hft9ae266.wl-tiwai@suse.de> (raw)
In-Reply-To: <862d7184dac6dea172d94b83f2ca7dd29136d2df.camel@linux.intel.com>
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(). Most of the legacy HD-audio codec
can work without the card object, including suspend/resume.
But this will be a more intensive surgery, and maybe not much worth
for the corner case, so I already applied your patch as is.
thanks,
Takashi
next prev parent reply other threads:[~2020-07-29 16:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-28 23:10 [PATCH] ALSA: hda: fix NULL pointer dereference during suspend Ranjani Sridharan
2020-07-29 7:48 ` Takashi Iwai
2020-07-29 9:39 ` Mark Brown
2020-07-29 15:03 ` Ranjani Sridharan
2020-07-29 16:06 ` Takashi Iwai [this message]
2020-07-30 13:07 ` Takashi Iwai
2020-07-30 17:33 ` Ranjani Sridharan
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