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ALSA: control: Don't embed ctl_dev

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Embedding the ctl_dev in the snd_card object may result in UAF when
the delayed kobj release is used; at the delayed kobj release, it
still accesses the struct device itself while the card memory (that
embeds the struct device) may be already gone.

As a workaround, detach the struct device from the card object by
allocating via the new snd_device_alloc() helper.  The rest are just
replacing ctl_dev access to the pointer.

This 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/20230816160252.23396-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2023-08-16 18:02:45 +02:00
parent 7f018db19b
commit 6a66b01de4
4 changed files with 12 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
include/sound/core.h
View file

@ -96,7 +96,7 @@ struct snd_card {
private data */
struct list_head devices; /* devices */
struct device ctl_dev; /* control device */
struct device *ctl_dev; /* control device */
unsigned int last_numid; /* last used numeric ID */
struct rw_semaphore controls_rwsem; /* controls lock (list and values) */
rwlock_t ctl_files_rwlock; /* ctl_files list lock */

14
sound/core/control.c
View file

@ -2389,7 +2389,7 @@ static int snd_ctl_dev_register(struct snd_device *device)
int err;
err = snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
&snd_ctl_f_ops, card, &card->ctl_dev);
&snd_ctl_f_ops, card, card->ctl_dev);
if (err < 0)
return err;
down_read(&card->controls_rwsem);
@ -2425,7 +2425,7 @@ static int snd_ctl_dev_disconnect(struct snd_device *device)
up_read(&snd_ctl_layer_rwsem);
up_read(&card->controls_rwsem);
return snd_unregister_device(&card->ctl_dev);
return snd_unregister_device(card->ctl_dev);
}
/*
@ -2447,7 +2447,7 @@ static int snd_ctl_dev_free(struct snd_device *device)
xa_destroy(&card->ctl_hash);
#endif
up_write(&card->controls_rwsem);
put_device(&card->ctl_dev);
put_device(card->ctl_dev);
return 0;
}
@ -2469,12 +2469,14 @@ int snd_ctl_create(struct snd_card *card)
if (snd_BUG_ON(card->number < 0 || card->number >= SNDRV_CARDS))
return -ENXIO;
snd_device_initialize(&card->ctl_dev, card);
dev_set_name(&card->ctl_dev, "controlC%d", card->number);
err = snd_device_alloc(&card->ctl_dev, card);
if (err < 0)
return err;
dev_set_name(card->ctl_dev, "controlC%d", card->number);
err = snd_device_new(card, SNDRV_DEV_CONTROL, card, &ops);
if (err < 0)
put_device(&card->ctl_dev);
put_device(card->ctl_dev);
return err;
}

4
sound/core/control_led.c
View file

@ -688,7 +688,7 @@ static void snd_ctl_led_sysfs_add(struct snd_card *card)
goto cerr;
led->cards[card->number] = led_card;
snprintf(link_name, sizeof(link_name), "led-%s", led->name);
WARN(sysfs_create_link(&card->ctl_dev.kobj, &led_card->dev.kobj, link_name),
WARN(sysfs_create_link(&card->ctl_dev->kobj, &led_card->dev.kobj, link_name),
"can't create symlink to controlC%i device\n", card->number);
WARN(sysfs_create_link(&led_card->dev.kobj, &card->card_dev.kobj, "card"),
"can't create symlink to card%i\n", card->number);
@ -714,7 +714,7 @@ static void snd_ctl_led_sysfs_remove(struct snd_card *card)
if (!led_card)
continue;
snprintf(link_name, sizeof(link_name), "led-%s", led->name);
sysfs_remove_link(&card->ctl_dev.kobj, link_name);
sysfs_remove_link(&card->ctl_dev->kobj, link_name);
sysfs_remove_link(&led_card->dev.kobj, "card");
device_unregister(&led_card->dev);
led->cards[card->number] = NULL;

2
sound/usb/media.c
View file

@ -163,7 +163,7 @@ void snd_media_stop_pipeline(struct snd_usb_substream *subs)
static int snd_media_mixer_init(struct snd_usb_audio *chip)
{
struct device *ctl_dev = &chip->card->ctl_dev;
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;