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ALSA: usb-audio: Fix control 'access overflow' errors from chmap 

commit c6dde8ffd0 upstream.

The current channel-map control implementation in USB-audio driver may
lead to an error message like
  "control 3:0:0:Playback Channel Map:0: access overflow"
when CONFIG_SND_CTL_VALIDATION is set.  It's because the chmap get
callback clears the whole array no matter which count is set, and
rather the false-positive detection.

This patch fixes the problem by clearing only the needed array range
at usb_chmap_ctl_get().

Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201211130048.6358-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Takashi Iwai 2020-12-11 14:00:48 +01:00 committed by Greg Kroah-Hartman
parent e72a55ea71
commit 5828ae0c19
1 changed files with 3 additions and 3 deletions
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6
sound/usb/stream.c
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@ -193,16 +193,16 @@ static int usb_chmap_ctl_get(struct snd_kcontrol *kcontrol,
struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
struct snd_usb_substream *subs = info->private_data;
struct snd_pcm_chmap_elem *chmap = NULL;
int i;
int i = 0;
memset(ucontrol->value.integer.value, 0,
sizeof(ucontrol->value.integer.value));
if (subs->cur_audiofmt)
chmap = subs->cur_audiofmt->chmap;
if (chmap) {
for (i = 0; i < chmap->channels; i++)
ucontrol->value.integer.value[i] = chmap->map[i];
}
for (; i < subs->channels_max; i++)
ucontrol->value.integer.value[i] = 0;
return 0;
}