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Subject[PATCH 4.14 093/193] ALSA: hda: Fix too short HDMI/DP chmap reporting
4.14-stable review patch.  If anyone has any objections, please let me know.


From: Takashi Iwai <>

commit c2432466f583cb719b35a41e757da587d9ab1d00 upstream.

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

- 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 <>
Signed-off-by: Takashi Iwai <>
Signed-off-by: Greg Kroah-Hartman <>

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;

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