[PATCH] ALSA: pcm: Need to check whether runtime is valid or not

[Chanho Park <chanho61.park@xxxxxxxxxxx>]

From: eunwoo kim <ew.kim@xxxxxxxxxxx>

Since snd_pcm_ioctl_sw_params_compat has no runtime variable check,
if application call the ioctl after close, it can make kernel crash.
So, snd_pcm_ioctl_sw_params_compat needs to check the runtime variable
at the beginning of the function.

Signed-off-by: eunwoo kim <ew.kim@xxxxxxxxxxx>
Signed-off-by: Chanho Park <chanho61.park@xxxxxxxxxxx>
---
 sound/core/pcm_compat.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c
index 590a46a9e78d..ff0de4252ff4 100644
--- a/sound/core/pcm_compat.c
+++ b/sound/core/pcm_compat.c
@@ -90,6 +90,9 @@ static int snd_pcm_ioctl_sw_params_compat(struct snd_pcm_substream *substream,
 	snd_pcm_uframes_t boundary;
 	int err;
 
+	if (!substream->runtime)
+		return -ENOTTY;
+
 	memset(&params, 0, sizeof(params));
 	if (get_user(params.tstamp_mode, &src->tstamp_mode) ||
 	    get_user(params.period_step, &src->period_step) ||
-- 
2.31.1