* [alsa-devel] [PATCH] ALSA: usb-audio: Don't create a mixer element with bogus volume range
@ 2020-02-14 14:49 Takashi Iwai
0 siblings, 0 replies; only message in thread
From: Takashi Iwai @ 2020-02-14 14:49 UTC (permalink / raw)
To: alsa-devel
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
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
sound/usb/mixer.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 81b2db0edd5f..906fd38ce647 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1674,6 +1674,16 @@ 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) {
--
2.16.4
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