[PATCH 4.1 54/78] ALSA: hda: fix possible NULL dereference

[Greg Kroah-Hartman]

4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Markus Osterhoff <linux-kernel@xxxxxxxxxx>

commit c7e69ae6b4ff49edf50180c0a32f3dd9d7967e31 upstream.

After a for-loop was replaced by list_for_each_entry, see
Commit bbbc7e8502c9 ("ALSA: hda - Allocate hda_pcm objects dynamically"),
Commit 751e2216899c ("ALSA: hda: fix possible null dereference"),
a possible NULL pointer dereference has been introduced; this patch adds
the NULL check on pcm->pcm, while leaving a potentially superfluous
check on pcm itself untouched.

Signed-off-by: Markus Osterhoff <linux-kernel@xxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 sound/pci/hda/hda_codec.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -3259,7 +3259,7 @@ static int add_std_chmaps(struct hda_cod
 			struct snd_pcm_chmap *chmap;
 			const struct snd_pcm_chmap_elem *elem;
 
-			if (!pcm || pcm->own_chmap ||
+			if (!pcm || !pcm->pcm || pcm->own_chmap ||
 			    !hinfo->substreams)
 				continue;
 			elem = hinfo->chmap ? hinfo->chmap : snd_pcm_std_chmaps;


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