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linux/sound/usb/media.c
Takashi Iwai bc41a7228c ALSA: pcm: Don't embed device 
So far we use the embedded struct device for each PCM substreams in
struct snd_pcm.  This may result in UAF when the delayed kobj release
is used; each corresponding struct device is still accessed at the
(delayed) device release, while the snd_pcm object may be already
gone.

As a workaround, detach the struct device from the snd_pcm object by
allocating via the new snd_device_alloc() helper.

A caveat is that we store the PCM substream pointer to drvdata since
the device resume and others require the access to it.

This patch is based on the fix Curtis posted initially.  In this
patch, the changes are split and use the new helper function instead.

Link: https://lore.kernel.org/r/20230801171928.1460120-1-cujomalainey@chromium.org
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Curtis Malainey <cujomalainey@chromium.org>
Tested-by: Curtis Malainey <cujomalainey@chromium.org>
Link: https://lore.kernel.org/r/20230816160252.23396-4-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2023-08-17 09:23:45 +02:00

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// SPDX-License-Identifier: GPL-2.0
/*
* media.c - Media Controller specific ALSA driver code
*
* Copyright (c) 2019 Shuah Khan <shuah@kernel.org>
*
*/
/*
* This file adds Media Controller support to the ALSA driver
* to use the Media Controller API to share the tuner with DVB
* and V4L2 drivers that control the media device.
*
* The media device is created based on the existing quirks framework.
* Using this approach, the media controller API usage can be added for
* a specific device.
*/
#include <linux/init.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <sound/pcm.h>
#include <sound/core.h>
#include "usbaudio.h"
#include "card.h"
#include "mixer.h"
#include "media.h"
int snd_media_stream_init(struct snd_usb_substream *subs, struct snd_pcm *pcm,
int stream)
{
struct media_device *mdev;
struct media_ctl *mctl;
struct device *pcm_dev = pcm->streams[stream].dev;
u32 intf_type;
int ret = 0;
u16 mixer_pad;
struct media_entity *entity;
mdev = subs->stream->chip->media_dev;
if (!mdev)
return 0;
if (subs->media_ctl)
return 0;
/* allocate media_ctl */
mctl = kzalloc(sizeof(*mctl), GFP_KERNEL);
if (!mctl)
return -ENOMEM;
mctl->media_dev = mdev;
if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
intf_type = MEDIA_INTF_T_ALSA_PCM_PLAYBACK;
mctl->media_entity.function = MEDIA_ENT_F_AUDIO_PLAYBACK;
mctl->media_pad.flags = MEDIA_PAD_FL_SOURCE;
mixer_pad = 1;
} else {
intf_type = MEDIA_INTF_T_ALSA_PCM_CAPTURE;
mctl->media_entity.function = MEDIA_ENT_F_AUDIO_CAPTURE;
mctl->media_pad.flags = MEDIA_PAD_FL_SINK;
mixer_pad = 2;
}
mctl->media_entity.name = pcm->name;
media_entity_pads_init(&mctl->media_entity, 1, &mctl->media_pad);
ret = media_device_register_entity(mctl->media_dev,
&mctl->media_entity);
if (ret)
goto free_mctl;
mctl->intf_devnode = media_devnode_create(mdev, intf_type, 0,
MAJOR(pcm_dev->devt),
MINOR(pcm_dev->devt));
if (!mctl->intf_devnode) {
ret = -ENOMEM;
goto unregister_entity;
}
mctl->intf_link = media_create_intf_link(&mctl->media_entity,
&mctl->intf_devnode->intf,
MEDIA_LNK_FL_ENABLED);
if (!mctl->intf_link) {
ret = -ENOMEM;
goto devnode_remove;
}
/* create link between mixer and audio */
media_device_for_each_entity(entity, mdev) {
switch (entity->function) {
case MEDIA_ENT_F_AUDIO_MIXER:
ret = media_create_pad_link(entity, mixer_pad,
&mctl->media_entity, 0,
MEDIA_LNK_FL_ENABLED);
if (ret)
goto remove_intf_link;
break;
}
}
subs->media_ctl = mctl;
return 0;
remove_intf_link:
media_remove_intf_link(mctl->intf_link);
devnode_remove:
media_devnode_remove(mctl->intf_devnode);
unregister_entity:
media_device_unregister_entity(&mctl->media_entity);
free_mctl:
kfree(mctl);
return ret;
}
void snd_media_stream_delete(struct snd_usb_substream *subs)
{
struct media_ctl *mctl = subs->media_ctl;
if (mctl) {
struct media_device *mdev;
mdev = mctl->media_dev;
if (mdev && media_devnode_is_registered(mdev->devnode)) {
media_devnode_remove(mctl->intf_devnode);
media_device_unregister_entity(&mctl->media_entity);
media_entity_cleanup(&mctl->media_entity);
}
kfree(mctl);
subs->media_ctl = NULL;
}
}
int snd_media_start_pipeline(struct snd_usb_substream *subs)
{
struct media_ctl *mctl = subs->media_ctl;
int ret = 0;
if (!mctl)
return 0;
mutex_lock(&mctl->media_dev->graph_mutex);
if (mctl->media_dev->enable_source)
ret = mctl->media_dev->enable_source(&mctl->media_entity,
&mctl->media_pipe);
mutex_unlock(&mctl->media_dev->graph_mutex);
return ret;
}
void snd_media_stop_pipeline(struct snd_usb_substream *subs)
{
struct media_ctl *mctl = subs->media_ctl;
if (!mctl)
return;
mutex_lock(&mctl->media_dev->graph_mutex);
if (mctl->media_dev->disable_source)
mctl->media_dev->disable_source(&mctl->media_entity);
mutex_unlock(&mctl->media_dev->graph_mutex);
}
static int snd_media_mixer_init(struct snd_usb_audio *chip)
{
struct device *ctl_dev = chip->card->ctl_dev;
struct media_intf_devnode *ctl_intf;
struct usb_mixer_interface *mixer;
struct media_device *mdev = chip->media_dev;
struct media_mixer_ctl *mctl;
u32 intf_type = MEDIA_INTF_T_ALSA_CONTROL;
int ret;
if (!mdev)
return -ENODEV;
ctl_intf = chip->ctl_intf_media_devnode;
if (!ctl_intf) {
ctl_intf = media_devnode_create(mdev, intf_type, 0,
MAJOR(ctl_dev->devt),
MINOR(ctl_dev->devt));
if (!ctl_intf)
return -ENOMEM;
chip->ctl_intf_media_devnode = ctl_intf;
}
list_for_each_entry(mixer, &chip->mixer_list, list) {
if (mixer->media_mixer_ctl)
continue;
/* allocate media_mixer_ctl */
mctl = kzalloc(sizeof(*mctl), GFP_KERNEL);
if (!mctl)
return -ENOMEM;
mctl->media_dev = mdev;
mctl->media_entity.function = MEDIA_ENT_F_AUDIO_MIXER;
mctl->media_entity.name = chip->card->mixername;
mctl->media_pad[0].flags = MEDIA_PAD_FL_SINK;
mctl->media_pad[1].flags = MEDIA_PAD_FL_SOURCE;
mctl->media_pad[2].flags = MEDIA_PAD_FL_SOURCE;
media_entity_pads_init(&mctl->media_entity, MEDIA_MIXER_PAD_MAX,
mctl->media_pad);
ret = media_device_register_entity(mctl->media_dev,
&mctl->media_entity);
if (ret) {
kfree(mctl);
return ret;
}
mctl->intf_link = media_create_intf_link(&mctl->media_entity,
&ctl_intf->intf,
MEDIA_LNK_FL_ENABLED);
if (!mctl->intf_link) {
media_device_unregister_entity(&mctl->media_entity);
media_entity_cleanup(&mctl->media_entity);
kfree(mctl);
return -ENOMEM;
}
mctl->intf_devnode = ctl_intf;
mixer->media_mixer_ctl = mctl;
}
return 0;
}
static void snd_media_mixer_delete(struct snd_usb_audio *chip)
{
struct usb_mixer_interface *mixer;
struct media_device *mdev = chip->media_dev;
if (!mdev)
return;
list_for_each_entry(mixer, &chip->mixer_list, list) {
struct media_mixer_ctl *mctl;
mctl = mixer->media_mixer_ctl;
if (!mixer->media_mixer_ctl)
continue;
if (media_devnode_is_registered(mdev->devnode)) {
media_device_unregister_entity(&mctl->media_entity);
media_entity_cleanup(&mctl->media_entity);
}
kfree(mctl);
mixer->media_mixer_ctl = NULL;
}
if (media_devnode_is_registered(mdev->devnode))
media_devnode_remove(chip->ctl_intf_media_devnode);
chip->ctl_intf_media_devnode = NULL;
}
int snd_media_device_create(struct snd_usb_audio *chip,
struct usb_interface *iface)
{
struct media_device *mdev;
struct usb_device *usbdev = interface_to_usbdev(iface);
int ret = 0;
/* usb-audio driver is probed for each usb interface, and
* there are multiple interfaces per device. Avoid calling
* media_device_usb_allocate() each time usb_audio_probe()
* is called. Do it only once.
*/
if (chip->media_dev) {
mdev = chip->media_dev;
goto snd_mixer_init;
}
mdev = media_device_usb_allocate(usbdev, KBUILD_MODNAME, THIS_MODULE);
if (IS_ERR(mdev))
return -ENOMEM;
/* save media device - avoid lookups */
chip->media_dev = mdev;
snd_mixer_init:
/* Create media entities for mixer and control dev */
ret = snd_media_mixer_init(chip);
/* media_device might be registered, print error and continue */
if (ret)
dev_err(&usbdev->dev,
"Couldn't create media mixer entities. Error: %d\n",
ret);
if (!media_devnode_is_registered(mdev->devnode)) {
/* don't register if snd_media_mixer_init() failed */
if (ret)
goto create_fail;
/* register media_device */
ret = media_device_register(mdev);
create_fail:
if (ret) {
snd_media_mixer_delete(chip);
media_device_delete(mdev, KBUILD_MODNAME, THIS_MODULE);
/* clear saved media_dev */
chip->media_dev = NULL;
dev_err(&usbdev->dev,
"Couldn't register media device. Error: %d\n",
ret);
return ret;
}
}
return ret;
}
void snd_media_device_delete(struct snd_usb_audio *chip)
{
struct media_device *mdev = chip->media_dev;
struct snd_usb_stream *stream;
/* release resources */
list_for_each_entry(stream, &chip->pcm_list, list) {
snd_media_stream_delete(&stream->substream[0]);
snd_media_stream_delete(&stream->substream[1]);
}
snd_media_mixer_delete(chip);
if (mdev) {
media_device_delete(mdev, KBUILD_MODNAME, THIS_MODULE);
chip->media_dev = NULL;
}
}
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