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    Subject[PATCH 5.4 125/388] ALSA: usb-audio: Dont create a mixer element with bogus volume range
    Date
    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


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