linux-kernel - [PATCH 5.1 18/96] ASoC: hda: fix unbalanced codec dev refcount for HDA_DEV

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Message-Id: <20190708150527.412917723@linuxfoundation.org>
Date:   Mon,  8 Jul 2019 17:12:50 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Takashi Iwai <tiwai@...e.de>, Mark Brown <broonie@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.1 18/96] ASoC: hda: fix unbalanced codec dev refcount for HDA_DEV_ASOC

[ Upstream commit d6947bb234dcc86e878d502516d0fb9d635aa2ae ]

HDA_DEV_ASOC type codec device refcounts are managed differently
from HDA_DEV_LEGACY devices. The refcount is released explicitly
in snd_hdac_ext_bus_device_remove() for ASOC type devices.
So, remove the put_device() call in snd_hda_codec_dev_free()
for such devices to make the refcount balanced. This will prevent
the NULL pointer exception when the codec driver is released
after the card is freed.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>
Reviewed-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 sound/pci/hda/hda_codec.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index b20eb7fc83eb..fcdf2cd3783b 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -840,7 +840,14 @@ static int snd_hda_codec_dev_free(struct snd_device *device)
 	if (codec->core.type == HDA_DEV_LEGACY)
 		snd_hdac_device_unregister(&codec->core);
 	codec_display_power(codec, false);
-	put_device(hda_codec_dev(codec));
+
+	/*
+	 * In the case of ASoC HD-audio bus, the device refcount is released in
+	 * snd_hdac_ext_bus_device_remove() explicitly.
+	 */
+	if (codec->core.type == HDA_DEV_LEGACY)
+		put_device(hda_codec_dev(codec));
+
 	return 0;
 }
 
-- 
2.20.1