[PATCH AUTOSEL 4.19 06/37] ALSA: hda: Fix race between creating and refreshing sysfs entries

Sasha Levin
2019-10-25T14:05:14Z

From: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>

[ Upstream commit ed180abba7f1fc3cf04ffa27767b1bcc8e8c842a ]

hda_widget_sysfs_reinit() can free underlying codec->widgets structure
on which widget_tree_create() operates. Add locking to prevent such
issues from happening.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110382
Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/sound/hdaudio.h | 1 +
sound/hda/hdac_device.c | 7 +++++++
sound/hda/hdac_sysfs.c | 3 +++
3 files changed, 11 insertions(+)

diff --git a/include/sound/hdaudio.h b/include/sound/hdaudio.h
index cd1773d0e08f0..0c68783be26fc 100644
--- a/include/sound/hdaudio.h
+++ b/include/sound/hdaudio.h
@@ -82,6 +82,7 @@ struct hdac_device {
bool link_power_control:1;

/* sysfs */
+ struct mutex widget_lock;
struct hdac_widget_tree *widgets;

/* regmap */
diff --git a/sound/hda/hdac_device.c b/sound/hda/hdac_device.c
index dbf02a3a8d2f2..020fbbbcf6f5c 100644
--- a/sound/hda/hdac_device.c
+++ b/sound/hda/hdac_device.c
@@ -55,6 +55,7 @@ int snd_hdac_device_init(struct hdac_device *codec, struct hdac_bus *bus,
codec->bus = bus;
codec->addr = addr;
codec->type = HDA_DEV_CORE;
+ mutex_init(&codec->widget_lock);
pm_runtime_set_active(&codec->dev);
pm_runtime_get_noresume(&codec->dev);
atomic_set(&codec->in_pm, 0);
@@ -141,7 +142,9 @@ int snd_hdac_device_register(struct hdac_device *codec)
err = device_add(&codec->dev);
if (err < 0)
return err;
+ mutex_lock(&codec->widget_lock);
err = hda_widget_sysfs_init(codec);
+ mutex_unlock(&codec->widget_lock);
if (err < 0) {
device_del(&codec->dev);
return err;
@@ -158,7 +161,9 @@ EXPORT_SYMBOL_GPL(snd_hdac_device_register);
void snd_hdac_device_unregister(struct hdac_device *codec)
{
if (device_is_registered(&codec->dev)) {
+ mutex_lock(&codec->widget_lock);
hda_widget_sysfs_exit(codec);
+ mutex_unlock(&codec->widget_lock);
device_del(&codec->dev);
snd_hdac_bus_remove_device(codec->bus, codec);
}
@@ -404,7 +409,9 @@ int snd_hdac_refresh_widgets(struct hdac_device *codec, bool sysfs)
}

if (sysfs) {
+ mutex_lock(&codec->widget_lock);
err = hda_widget_sysfs_reinit(codec, start_nid, nums);
+ mutex_unlock(&codec->widget_lock);
if (err < 0)
return err;
}
diff --git a/sound/hda/hdac_sysfs.c b/sound/hda/hdac_sysfs.c
index fb2aa344981e6..909d5ef1179c9 100644
--- a/sound/hda/hdac_sysfs.c
+++ b/sound/hda/hdac_sysfs.c
@@ -395,6 +395,7 @@ static int widget_tree_create(struct hdac_device *codec)
return 0;
}

+/* call with codec->widget_lock held */
int hda_widget_sysfs_init(struct hdac_device *codec)
{
int err;
@@ -411,11 +412,13 @@ int hda_widget_sysfs_init(struct hdac_device *codec)
return 0;
}

+/* call with codec->widget_lock held */
void hda_widget_sysfs_exit(struct hdac_device *codec)
{
widget_tree_free(codec);
}

+/* call with codec->widget_lock held */
int hda_widget_sysfs_reinit(struct hdac_device *codec,
hda_nid_t start_nid, int num_nodes)
{
--
2.20.1