On Thu, Mar 31, 2022 at 12:27 AM Takashi Iwai <tiwai@xxxxxxx> wrote: > > 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@xxxxxxxxxxxxxxx> > > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > Signed-off-by: Won Chung <wonchung@xxxxxxxxxx> > > --- > > - Add "Fixes" tag > > - Send to stable@xxxxxxxxxxxxxxx > > You rather need to add "Cc: stable@xxxxxxxxxxxxxxx" 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 Hi Takashi, When I try using component_add in a different driver (usb4 in my case), I think dev->driver here is NULL because the i915 drivers do not have their component master fully bound when this new component is registered. When I test it, it seems to be causing a crash. Would it be okay for me to resend a new patch with the flags corrected? I have mistakenly added Heikki and Mika as "Signed-off-by" instead of "Suggested-by". I am sorry for that. Thanks, Won