Re: [PATCH] ALSA: control: Don't add invalid kcontrols to LED layer

[Jaroslav Kysela]

On 8/27/26 13:39, Takashi Iwai wrote:
> The kcontrol LED state layer tries to track the all associated
> kcontrol elements with naive assumptions that they are readable.
> But one can create a write-only element that has no get callback (even
> a user element can do it), and this may lead to a NULL dereference at
> the call chain of snd_ctl_led_notify(), as found by syzkaller.
>
> For avoiding the Oops, add a sanity check of the kcontrol's info and
> get callbacks, and just skip the invalid kcontrols before assigning
> the kctl to the LED layer.
>
> Reported-by: syzbot+b7fe2760ea6f1ee44b4d@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://lore.kernel.org/6a9007b3.1d9ded08.62e62.00cd.GAE@xxxxxxxxxx
> Fixes: 22d8de62f11b ("ALSA: control - add generic LED trigger module as the new control layer")
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>

Reviewed-by: Jaroslav Kysela <perex@xxxxxxxx>

--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat