ALSA: timer: fix NULL pointer dereference in read()/ioctl() race

[cascardo/linux.git] / sound / core / timer.c

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 9a6157e..2706061 100644 (file)
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -294,8 +294,21 @@ int snd_timer_open(struct snd_timer_instance **ti,
                get_device(&timer->card->card_dev);
        timeri->slave_class = tid->dev_sclass;
        timeri->slave_id = slave_id;
-       if (list_empty(&timer->open_list_head) && timer->hw.open)
-               timer->hw.open(timer);
+
+       if (list_empty(&timer->open_list_head) && timer->hw.open) {
+               int err = timer->hw.open(timer);
+               if (err) {
+                       kfree(timeri->owner);
+                       kfree(timeri);
+
+                       if (timer->card)
+                               put_device(&timer->card->card_dev);
+                       module_put(timer->module);
+                       mutex_unlock(&register_mutex);
+                       return err;
+               }
+       }
+
        list_add_tail(&timeri->open_list, &timer->open_list_head);
        snd_timer_check_master(timeri);
        mutex_unlock(&register_mutex);
@@ -813,6 +826,7 @@ int snd_timer_new(struct snd_card *card, char *id, struct snd_timer_id *tid,
        timer->tmr_subdevice = tid->subdevice;
        if (id)
                strlcpy(timer->id, id, sizeof(timer->id));
+       timer->sticks = 1;
        INIT_LIST_HEAD(&timer->device_list);
        INIT_LIST_HEAD(&timer->open_list_head);
        INIT_LIST_HEAD(&timer->active_list_head);
@@ -1958,6 +1972,7 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer,
                tu->qused--;
                spin_unlock_irq(&tu->qlock);
 
+               mutex_lock(&tu->ioctl_lock);
                if (tu->tread) {
                        if (copy_to_user(buffer, &tu->tqueue[qhead],
                                         sizeof(struct snd_timer_tread)))
@@ -1967,6 +1982,7 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer,
                                         sizeof(struct snd_timer_read)))
                                err = -EFAULT;
                }
+               mutex_unlock(&tu->ioctl_lock);
 
                spin_lock_irq(&tu->qlock);
                if (err < 0)