linux-kernel - [PATCH 1/1] sound/hda/hdac_stream: Avoid NULL pointer dereference

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Date:   Mon, 11 Mar 2019 21:53:57 +0100
From:   Mariusz Ceier <mceier+kernel@...il.com>
To:     Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
        Ravindra Lokhande <rlokhande@...dia.com>,
        Sameer Pujar <spujar@...dia.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Mohan Kumar D <mkumard@...dia.com>,
        Keyon Jie <yang.jie@...ux.intel.com>,
        Mariusz Ceier <mceier+kernel@...il.com>,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] sound/hda/hdac_stream: Avoid NULL pointer dereference

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.

Signed-off-by: Mariusz Ceier <mceier+kernel@...il.com>
---
 sound/hda/hdac_stream.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sound/hda/hdac_stream.c b/sound/hda/hdac_stream.c
index f5dd288d1a7a..76e9b41fcea2 100644
--- 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 */
-- 
2.21.0