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: Alexander 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: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/pci/hda/hda_generic.c b/sound/pci/hda/hda_generic.c
index 3bf5e341070388864b8594d75a6959940190b453..fc114e5224806f44cfffd3797997c17fc0a9087b 100644 (file)
--- a/sound/pci/hda/hda_generic.c
+++ b/sound/pci/hda/hda_generic.c
@@ -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;
 }
 
 /**

diff --git a/sound/pci/hda/hda_generic.h b/sound/pci/hda/hda_generic.h
index 8e1bc8ea74fc3269f60904224dce91eedce01958..34eba40cc6e67b2573482ccb2534d8636c245301 100644 (file)
--- a/sound/pci/hda/hda_generic.h
+++ b/sound/pci/hda/hda_generic.h
@@ -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 */