Commit 549f8ffc authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: hda: Fix UAF of leds class devs at unbinding 



The LED class devices that are created by HD-audio codec drivers are
registered via devm_led_classdev_register() and associated with the
HD-audio codec device.  Unfortunately, it turned out that the devres
release doesn't work for this case; namely, since the codec resource
release happens before the devm call chain, it triggers a NULL
dereference or a UAF for a stale set_brightness_delay callback.

For fixing the bug, this patch changes the LED class device register
and unregister in a manual manner without devres, keeping the
instances in hda_gen_spec.

Reported-by: default avatarAlexander Sergeyev <sergeev917@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220111195229.a77wrpjclqwrx4bx@localhost.localdomain
Link: https://lore.kernel.org/r/20220126145011.16728-1-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent e783362e

sound/pci/hda/hda_generic.c

+15 −2
Original line number Diff line number Diff line
@@ -91,6 +91,12 @@ static void snd_hda_gen_spec_free(struct hda_gen_spec *spec) 
	free_kctls(spec);

	snd_array_free(&spec->paths);

	snd_array_free(&spec->loopback_list);

#ifdef CONFIG_SND_HDA_GENERIC_LEDS

	if (spec->led_cdevs[LED_AUDIO_MUTE])

		led_classdev_unregister(spec->led_cdevs[LED_AUDIO_MUTE]);

	if (spec->led_cdevs[LED_AUDIO_MICMUTE])

		led_classdev_unregister(spec->led_cdevs[LED_AUDIO_MICMUTE]);

#endif

}



/*
@@ -3922,7 +3928,10 @@ static int create_mute_led_cdev(struct hda_codec *codec, 
						enum led_brightness),

				bool micmute)

{

	struct hda_gen_spec *spec = codec->spec;

	struct led_classdev *cdev;

	int idx = micmute ? LED_AUDIO_MICMUTE : LED_AUDIO_MUTE;

	int err;



	cdev = devm_kzalloc(&codec->core.dev, sizeof(*cdev), GFP_KERNEL);

	if (!cdev)
@@ -3932,10 +3941,14 @@ static int create_mute_led_cdev(struct hda_codec *codec, 
	cdev->max_brightness = 1;

	cdev->default_trigger = micmute ? "audio-micmute" : "audio-mute";

	cdev->brightness_set_blocking = callback;

	cdev->brightness = ledtrig_audio_get(micmute ? LED_AUDIO_MICMUTE : LED_AUDIO_MUTE);

	cdev->brightness = ledtrig_audio_get(idx);

	cdev->flags = LED_CORE_SUSPENDRESUME;



	return devm_led_classdev_register(&codec->core.dev, cdev);

	err = led_classdev_register(&codec->core.dev, cdev);

	if (err < 0)

		return err;

	spec->led_cdevs[idx] = cdev;

	return 0;

}



/**

sound/pci/hda/hda_generic.h

+3 −0
Original line number Diff line number Diff line
@@ -294,6 +294,9 @@ struct hda_gen_spec { 
				   struct hda_jack_callback *cb);

	void (*mic_autoswitch_hook)(struct hda_codec *codec,

				    struct hda_jack_callback *cb);



	/* leds */

	struct led_classdev *led_cdevs[NUM_AUDIO_LEDS];

};



/* values for add_stereo_mix_input flag */