[PATCH AUTOSEL 5.4 131/330] ALSA: usb-audio: Don't create a mixer element with bogus volume range

Sasha Levin
2020-09-18T03:07:14Z

From: Takashi Iwai <tiwai@suse.de>

[ Upstream commit e9a0ef0b5ddcbc0d56c65aefc0f18d16e6f71207 ]

Some USB-audio descriptors provide a bogus volume range (e.g. volume
min and max are identical), which confuses user-space.
This patch makes the driver skipping such a control element.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=206221
Link: https://lore.kernel.org/r/20200214144928.23628-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/usb/mixer.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 9079c380228fc..8aa96ed0b1b56 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1684,6 +1684,16 @@ static void __build_feature_ctl(struct usb_mixer_interface *mixer,
/* get min/max values */
get_min_max_with_quirks(cval, 0, kctl);

+ /* skip a bogus volume range */
+ if (cval->max <= cval->min) {
+ usb_audio_dbg(mixer->chip,
+ "[%d] FU [%s] skipped due to invalid volume\n",
+ cval->head.id, kctl->id.name);
+ snd_ctl_free_one(kctl);
+ return;
+ }
+
+
if (control == UAC_FU_VOLUME) {
check_mapped_dB(map, cval);
if (cval->dBmin < cval->dBmax || !cval->initialized) {
--
2.25.1