linux-kernel - [PATCH v2 01/11] ASoC: Intel: Skylake: Initialize lists before access so they are safe to use

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Date:   Mon, 17 Jun 2019 13:36:34 +0200
From:   Amadeusz Sławiński 
        <amadeuszx.slawinski@...ux.intel.com>
To:     alsa-devel@...a-project.org
Cc:     Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Jie Yang <yang.jie@...ux.intel.com>,
        Cezary Rojewski <cezary.rojewski@...el.com>,
        linux-kernel@...r.kernel.org,
        Amadeusz Sławiński 
        <amadeuszx.slawinski@...ux.intel.com>
Subject: [PATCH v2 01/11] ASoC: Intel: Skylake: Initialize lists before access so they are safe to use

If skl_probe_work() was not run driver ends up dereferencing NULL
pointer when operating on lists in skl_platform_unregister().
To fix this initialize lists in skl_create(). Also run
cancel_work_sync() before all cleanup functions, so we don't end up
unnecessarily running probe work.

Easily reproducible with:
while true; do modprobe snd_soc_skl; rmmod snd_soc_skl; done
(with the assumption that relevant drivers are added to blacklist on
system boot)

Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@...ux.intel.com>
---
 sound/soc/intel/skylake/skl-pcm.c | 3 ---
 sound/soc/intel/skylake/skl.c     | 5 ++++-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/sound/soc/intel/skylake/skl-pcm.c b/sound/soc/intel/skylake/skl-pcm.c
index 8b7232d3ffee..489ecef311ad 100644
--- a/sound/soc/intel/skylake/skl-pcm.c
+++ b/sound/soc/intel/skylake/skl-pcm.c
@@ -1477,9 +1477,6 @@ int skl_platform_register(struct device *dev)
 	struct hdac_bus *bus = dev_get_drvdata(dev);
 	struct skl *skl = bus_to_skl(bus);
 
-	INIT_LIST_HEAD(&skl->ppl_list);
-	INIT_LIST_HEAD(&skl->bind_list);
-
 	skl->dais = kmemdup(skl_platform_dai, sizeof(skl_platform_dai),
 			    GFP_KERNEL);
 	if (!skl->dais) {
diff --git a/sound/soc/intel/skylake/skl.c b/sound/soc/intel/skylake/skl.c
index fc79401cd474..cae97c65eef8 100644
--- a/sound/soc/intel/skylake/skl.c
+++ b/sound/soc/intel/skylake/skl.c
@@ -430,7 +430,6 @@ static int skl_free(struct hdac_bus *bus)
 
 	snd_hdac_ext_bus_exit(bus);
 
-	cancel_work_sync(&skl->probe_work);
 	if (IS_ENABLED(CONFIG_SND_SOC_HDAC_HDMI)) {
 		snd_hdac_display_power(bus, HDA_CODEC_IDX_CONTROLLER, false);
 		snd_hdac_i915_exit(bus);
@@ -859,6 +858,9 @@ static int skl_create(struct pci_dev *pci,
 	hbus = skl_to_hbus(skl);
 	bus = skl_to_bus(skl);
 
+	INIT_LIST_HEAD(&skl->ppl_list);
+	INIT_LIST_HEAD(&skl->bind_list);
+
 #if IS_ENABLED(CONFIG_SND_SOC_INTEL_SKYLAKE_HDAUDIO_CODEC)
 	ext_ops = snd_soc_hdac_hda_get_ops();
 #endif
@@ -1108,6 +1110,7 @@ static void skl_remove(struct pci_dev *pci)
 	struct hdac_bus *bus = pci_get_drvdata(pci);
 	struct skl *skl = bus_to_skl(bus);
 
+	cancel_work_sync(&skl->probe_work);
 	release_firmware(skl->tplg);
 
 	pm_runtime_get_noresume(&pci->dev);
-- 
2.17.1