ALSA: timer: Fix zero-division by continue of uninitialized instance

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

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 2706061fc1eae3fc5028365952de4796253add74..fc144f43faa67c177dba17a40c246a2af3edef7c 100644 (file)
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -35,6 +35,9 @@
 #include <sound/initval.h>
 #include <linux/kmod.h>
 
+/* internal flags */
+#define SNDRV_TIMER_IFLG_PAUSED                0x00010000
+
 #if IS_ENABLED(CONFIG_SND_HRTIMER)
 #define DEFAULT_TIMER_LIMIT 4
 #else
@@ -539,6 +542,10 @@ static int snd_timer_stop1(struct snd_timer_instance *timeri, bool stop)
                }
        }
        timeri->flags &= ~(SNDRV_TIMER_IFLG_RUNNING | SNDRV_TIMER_IFLG_START);
+       if (stop)
+               timeri->flags &= ~SNDRV_TIMER_IFLG_PAUSED;
+       else
+               timeri->flags |= SNDRV_TIMER_IFLG_PAUSED;
        snd_timer_notify1(timeri, stop ? SNDRV_TIMER_EVENT_STOP :
                          SNDRV_TIMER_EVENT_CONTINUE);
  unlock:
@@ -600,6 +607,10 @@ int snd_timer_stop(struct snd_timer_instance *timeri)
  */
 int snd_timer_continue(struct snd_timer_instance *timeri)
 {
+       /* timer can continue only after pause */
+       if (!(timeri->flags & SNDRV_TIMER_IFLG_PAUSED))
+               return -EINVAL;
+
        if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
                return snd_timer_start_slave(timeri, false);
        else
@@ -1831,6 +1842,9 @@ static int snd_timer_user_continue(struct file *file)
        tu = file->private_data;
        if (!tu->timeri)
                return -EBADFD;
+       /* start timer instead of continue if it's not used before */
+       if (!(tu->timeri->flags & SNDRV_TIMER_IFLG_PAUSED))
+               return snd_timer_user_start(file);
        tu->timeri->lost = 0;
        return (err = snd_timer_continue(tu->timeri)) < 0 ? err : 0;
 }