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    Subject[PATCH 4.9 048/138] ALSA: hda: Fix too short HDMI/DP chmap reporting
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

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

    From: Takashi Iwai <tiwai@suse.de>

    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
    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>
    Signed-off-by: Takashi Iwai <tiwai@suse.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    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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