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control: use reference-counted pid
Instead of storing the PID number, take a reference to the task's pid structure. This protects against duplicates due to PID overflows, and using pid_vnr() ensures that the PID returned by snd_ctl_elem_info() is correct as seen from the current namespace. Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
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@ -86,10 +86,12 @@ struct snd_kctl_event {
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#define snd_kctl_event(n) list_entry(n, struct snd_kctl_event, list)
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struct pid;
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struct snd_ctl_file {
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struct list_head list; /* list of all control files */
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struct snd_card *card;
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pid_t pid;
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struct pid *pid;
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int prefer_pcm_subdevice;
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int prefer_rawmidi_subdevice;
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wait_queue_head_t change_sleep;
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@ -75,7 +75,7 @@ static int snd_ctl_open(struct inode *inode, struct file *file)
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ctl->card = card;
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ctl->prefer_pcm_subdevice = -1;
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ctl->prefer_rawmidi_subdevice = -1;
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ctl->pid = current->pid;
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ctl->pid = get_pid(task_pid(current));
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file->private_data = ctl;
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write_lock_irqsave(&card->ctl_files_rwlock, flags);
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list_add_tail(&ctl->list, &card->ctl_files);
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@ -125,6 +125,7 @@ static int snd_ctl_release(struct inode *inode, struct file *file)
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control->vd[idx].owner = NULL;
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up_write(&card->controls_rwsem);
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snd_ctl_empty_read_queue(ctl);
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put_pid(ctl->pid);
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kfree(ctl);
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module_put(card->module);
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snd_card_file_remove(card, file);
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@ -672,7 +673,7 @@ static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
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info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
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if (vd->owner == ctl)
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info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;
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info->owner = vd->owner->pid;
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info->owner = pid_vnr(vd->owner->pid);
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} else {
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info->owner = -1;
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}
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@ -809,7 +809,7 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
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card = pcm->card;
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read_lock(&card->ctl_files_rwlock);
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list_for_each_entry(kctl, &card->ctl_files, list) {
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if (kctl->pid == current->pid) {
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if (kctl->pid == task_pid(current)) {
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prefer_subdevice = kctl->prefer_pcm_subdevice;
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if (prefer_subdevice != -1)
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break;
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@ -415,7 +415,7 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
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subdevice = -1;
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read_lock(&card->ctl_files_rwlock);
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list_for_each_entry(kctl, &card->ctl_files, list) {
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if (kctl->pid == current->pid) {
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if (kctl->pid == task_pid(current)) {
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subdevice = kctl->prefer_rawmidi_subdevice;
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if (subdevice != -1)
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break;
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