linux-kernel - [PATCH 5.10 157/199] ASoC: SOF: Intel: fix page fault at probe if i915 init fails

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Date:   Mon, 25 Jan 2021 19:39:39 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jaroslav Kysela <perex@...ex.cz>,
        Kai Vehmanen <kai.vehmanen@...ux.intel.com>,
        Rander Wang <rander.wang@...el.com>,
        Libin Yang <libin.yang@...el.com>,
        Bard Liao <bard.liao@...el.com>,
        Mark Brown <broonie@...nel.org>
Subject: [PATCH 5.10 157/199] ASoC: SOF: Intel: fix page fault at probe if i915 init fails

From: Kai Vehmanen <kai.vehmanen@...ux.intel.com>

commit 9c25af250214e45f6d1c21ff6239a1ffeeedf20e upstream.

The earlier commit to fix runtime PM in case i915 init fails,
introduces a possibility to hit a page fault.

snd_hdac_ext_bus_device_exit() is designed to be called from
dev.release(). Calling it outside device reference counting, is
not safe and may lead to calling the device_exit() function
twice. Additionally, as part of ext_bus_device_init(), the device
is also registered with snd_hdac_device_register(). Thus before
calling device_exit(), the device must be removed from device
hierarchy first.

Fix the issue by rolling back init actions by calling
hdac_device_unregister() and then releasing device with put_device().
This matches with existing code in hdac-ext module.

To complete the fix, add handling for the case where
hda_codec_load_module() returns -ENODEV, and clean up the hdac_ext
resources also in this case.

In future work, hdac-ext interface should be extended to allow clients
more flexibility to handle the life-cycle of individual devices, beyond
just the current snd_hdac_ext_bus_device_remove(), which removes all
devices.

BugLink: https://github.com/thesofproject/linux/issues/2646
Reported-by: Jaroslav Kysela <perex@...ex.cz>
Fixes: 6c63c954e1c5 ("ASoC: SOF: fix a runtime pm issue in SOF when HDMI codec doesn't work")
Signed-off-by: Kai Vehmanen <kai.vehmanen@...ux.intel.com>
Reviewed-by: Rander Wang <rander.wang@...el.com>
Reviewed-by: Libin Yang <libin.yang@...el.com>
Reviewed-by: Bard Liao <bard.liao@...el.com>
Link: https://lore.kernel.org/r/20210113150715.3992635-1-kai.vehmanen@linux.intel.com
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/soc/sof/intel/hda-codec.c |   18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

--- a/sound/soc/sof/intel/hda-codec.c
+++ b/sound/soc/sof/intel/hda-codec.c
@@ -156,7 +156,8 @@ static int hda_codec_probe(struct snd_so
 		if (!hdev->bus->audio_component) {
 			dev_dbg(sdev->dev,
 				"iDisp hw present but no driver\n");
-			goto error;
+			ret = -ENOENT;
+			goto out;
 		}
 		hda_priv->need_display_power = true;
 	}
@@ -173,24 +174,23 @@ static int hda_codec_probe(struct snd_so
 		 * other return codes without modification
 		 */
 		if (ret == 0)
-			goto error;
+			ret = -ENOENT;
 	}

-	return ret;
-
-error:
-	snd_hdac_ext_bus_device_exit(hdev);
-	return -ENOENT;
-
+out:
+	if (ret < 0) {
+		snd_hdac_device_unregister(hdev);
+		put_device(&hdev->dev);
+	}
 #else
 	hdev = devm_kzalloc(sdev->dev, sizeof(*hdev), GFP_KERNEL);
 	if (!hdev)
 		return -ENOMEM;

 	ret = snd_hdac_ext_bus_device_init(&hbus->core, address, hdev, HDA_DEV_ASOC);
+#endif

 	return ret;
-#endif
 }

 /* Codec initialization */