Re: [PATCH v2] sound/hda: Add NULL check to component match callback function

Takashi Iwai
2022-03-31T07:27:46Z

On Wed, 30 Mar 2022 23:19:13 +0200,
Won Chung wrote:
>
> Component match callback function needs to check if expected data is
> passed to it. Without this check, it can cause a NULL pointer
> dereference when another driver registers a component before i915
> drivers have their component master fully bind.
>
> Fixes: 7b882fe3e3e8b ("ALSA: hda - handle multiple i915 device instances")
> Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> Signed-off-by: Won Chung <wonchung@google.com>
> ---
> - Add "Fixes" tag
> - Send to stable@vger.kernel.org

You rather need to add "Cc: stable@vger.kernel.org" line to the patch
itself (around sign-off block), not actually Cc'ing the mail.
I edited manually, but please do it so at the next time.

Although I applied the patch as-is now, I wonder...

> - if (!strcmp(dev->driver->name, "i915") &&
> + if (dev->driver && !strcmp(dev->driver->name, "i915") &&

Can NULL dev->driver be really seen? I thought the components are
added by the drivers, hence they ought to have the driver field set.
But there can be corner cases I overlooked.

thanks,

Takashi