Date 27.6.2014 20:13, JongHo Kim wrote:

...

From a46df32a4fc184364be45ffe8957d5a20818d979 Mon Sep 17 00:00:00 2001

From: JongHo Kim furmuwon@gmail.com Date: Sat, 28 Jun 2014 02:49:13 +0900 Subject: [PATCH] ALSA: Remove the runtime local variable in snd_pcm_period_elapsed

The local runtime variable in snd_pcm_period_elapsed has the value of substream->runtime. If the substream->runtime memory was freed, The local runtime variable can point the invalid memory. If do not fix this, can refer to freed memory. This patch remove local runtime variable and check the NULL directly.

This patch looks wrong. Besides the wrong fix, the elapsed function MUST NOT be called when the stream is inactive (stopped). The PCM core functions calls the stop callback for the lowlevel drivers. It appears like an issue in the hardware driver.

Jaroslav

Signed-off-by: JongHo Kim furmuwon@gmail.com

sound/core/pcm_lib.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 9acc77e..c3de2d3 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -1836,15 +1836,13 @@ EXPORT_SYMBOL(snd_pcm_lib_ioctl); */ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream) {

• struct snd_pcm_runtime *runtime; unsigned long flags;

  if (PCM_RUNTIME_CHECK(substream)) return;

• runtime = substream->runtime;

• if (runtime->transfer_ack_begin)

• runtime->transfer_ack_begin(substream);
  

• if (substream->runtime && substream->runtime->transfer_ack_begin)

• substream->runtime->transfer_ack_begin(substream);
  
  

  snd_pcm_stream_lock_irqsave(substream, flags); if (!snd_pcm_running(substream) ||

@@ -1855,9 +1853,11 @@ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream) snd_timer_interrupt(substream->timer, 1); _end: snd_pcm_stream_unlock_irqrestore(substream, flags);

• if (runtime->transfer_ack_end)

• runtime->transfer_ack_end(substream);
  

• kill_fasync(&runtime->fasync, SIGIO, POLL_IN);

• if (substream->runtime && substream->runtime->transfer_ack_end)

• substream->runtime->transfer_ack_end(substream);
  

• if (substream->runtime)

• kill_fasync(&substream->runtime->fasync, SIGIO, POLL_IN);
  

  }

  EXPORT_SYMBOL(snd_pcm_period_elapsed);