From c2432466f583cb719b35a41e757da587d9ab1d00 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Fri, 17 Nov 2017 12:08:40 +0100
Subject: [PATCH] ALSA: hda: Fix too short HDMI/DP chmap reporting
Patch-mainline: v4.15-rc1
References: bsc#1051510
Git-commit: c2432466f583cb719b35a41e757da587d9ab1d00

We got a regression report about the HD-audio HDMI chmap, where some
surround channels are reported as UNKNOWN.  The git bisection pointed
the culprit at the commit 9b3dc8aa3fb1 ("ALSA: hda - Register chmap
obj as priv data instead of codec").  The story behind scene is like
This: 

- While moving the code out of the legacy HDA to the HDA common place,
  the patch modifies the code to obtain the chmap array indirectly in
  a byte array, and it expands it to kctl value array.
- At the latter operation, the size of the array is wrongly passed by
  sizeof() to the pointer.
- It can be 4 on 32bit arch, thus too short for 6+ channels.
  (And that's the reason why it didn't hit other persons; it's 8 on
  64bit arch, thus it's usually enough.)

The code was further changed meanwhile, but the problem persisted.
Let's fix it by correctly evaluating the array size.

Fixes: 9b3dc8aa3fb1 ("ALSA: hda - Register chmap obj as priv data instead of codec")
Reported-by: VDR User <user.vdr@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

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

--- a/sound/hda/hdmi_chmap.c
+++ b/sound/hda/hdmi_chmap.c
@@ -746,7 +746,7 @@ static int hdmi_chmap_ctl_get(struct snd
 	memset(pcm_chmap, 0, sizeof(pcm_chmap));
 	chmap->ops.get_chmap(chmap->hdac, pcm_idx, pcm_chmap);
 
-	for (i = 0; i < sizeof(chmap); i++)
+	for (i = 0; i < ARRAY_SIZE(pcm_chmap); i++)
 		ucontrol->value.integer.value[i] = pcm_chmap[i];
 
 	return 0;