tree ce7971407b6347f7f36b535ab97bd3796bc23154
parent 607184cb1635eaee239fe3fb9648a8b82a5232d7
author Takashi Iwai <tiwai@suse.de> 1607691648 +0100
committer Takashi Iwai <tiwai@suse.de> 1607691835 +0100

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

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>