[ALSA] sound: fix PCM substream list

If snd_pcm_new_stream() fails to initalize a substream (if
snd_pcm_substream_proc_init() returns error), snd_pcm_new_stream()
immediately return without unlinking that kfree()d substram.
It causes oops when snd_pcm_free() iterates the list of substream to
free them by invalid reference.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

1 files changed, 4 insertions, 0 deletions

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 5ac6e19ccb41..8e0189885516 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -640,6 +640,10 @@ int snd_pcm_new_stream(struct snd_pcm *pcm, int stream, int substream_count)
                 err = snd_pcm_substream_proc_init(substream);
                 if (err < 0) {
                         snd_printk(KERN_ERR "Error in snd_pcm_stream_proc_init\n");
+                        if (prev == NULL)
+                                pstr->substream = NULL;
+                        else
+                                prev->next = NULL;
                         kfree(substream);
                         return err;
                 }