ALSA: hda: Avoid NULL pointer dereference at snd_hdac_stream_start()

For ca0132 codec, azx_dev->stream is NULL during firmware loading.
Calling snd_hdac_get_stream_stripe_ctl unconditionally causes NULL
pointer dereference in that function.

Fixes: 9b6f7e7a296e ("ALSA: hda: program stripe bits for controller")
Signed-off-by: Mariusz Ceier <mceier+kernel@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/hda/hdac_stream.c b/sound/hda/hdac_stream.c
index f5dd288d1a7a39d9454bd1cf94a8e744601c07c1..76e9b41fcea2cb662966d325f20f48d9ce6b8a95 100644 (file)
--- a/sound/hda/hdac_stream.c
+++ b/sound/hda/hdac_stream.c
@@ -95,7 +95,10 @@ void snd_hdac_stream_start(struct hdac_stream *azx_dev, bool fresh_start)
                              1 << azx_dev->index,
                              1 << azx_dev->index);
        /* set stripe control */
-       stripe_ctl = snd_hdac_get_stream_stripe_ctl(bus, azx_dev->substream);
+       if (azx_dev->substream)
+               stripe_ctl = snd_hdac_get_stream_stripe_ctl(bus, azx_dev->substream);
+       else
+               stripe_ctl = 0;
        snd_hdac_stream_updateb(azx_dev, SD_CTL_3B, SD_CTL_STRIPE_MASK,
                                stripe_ctl);
        /* set DMA start and interrupt mask */