This reverts commit 89b593c30e83 ("ALSA: usb-audio: purge needless variable length array"). The patch turned out to cause a severe regression, triggering an Oops at snd_usb_ctl_msg(). It was overseen that snd_usb_ctl_msg() writes back the response to the given buffer, while the patch changed it to a read-only const buffer. (One should always double-check when an extra pointer cast is present...)

As a simple fix, just revert the affected commit. It was merely a cleanup. Although it brings VLA again, it's clearer as a fix. We'll address the VLA later in another patch.

Fixes: 89b593c30e83 ("ALSA: usb-audio: purge needless variable length array") Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=195875 Cc: stable@vger.kernel.org # v4.11+ Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/usb/mixer_us16x08.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/sound/usb/mixer_us16x08.c b/sound/usb/mixer_us16x08.c index dc48eedea92e..29d2c9282987 100644 --- a/sound/usb/mixer_us16x08.c +++ b/sound/usb/mixer_us16x08.c @@ -698,12 +698,12 @@ static int snd_us16x08_meter_get(struct snd_kcontrol *kcontrol, struct snd_usb_audio *chip = elem->head.mixer->chip; struct snd_us16x08_meter_store *store = elem->private_data; u8 meter_urb[64]; - char tmp[sizeof(mix_init_msg2)] = {0}; + char tmp[max(sizeof(mix_init_msg1), sizeof(mix_init_msg2))];

switch (kcontrol->private_value) { case 0: - snd_us16x08_send_urb(chip, (char *)mix_init_msg1, - sizeof(mix_init_msg1)); + memcpy(tmp, mix_init_msg1, sizeof(mix_init_msg1)); + snd_us16x08_send_urb(chip, tmp, 4); snd_us16x08_recv_urb(chip, meter_urb, sizeof(meter_urb)); kcontrol->private_value++; @@ -721,7 +721,7 @@ static int snd_us16x08_meter_get(struct snd_kcontrol *kcontrol, case 3: memcpy(tmp, mix_init_msg2, sizeof(mix_init_msg2)); tmp[2] = snd_get_meter_comp_index(store); - snd_us16x08_send_urb(chip, tmp, sizeof(mix_init_msg2)); + snd_us16x08_send_urb(chip, tmp, 10); snd_us16x08_recv_urb(chip, meter_urb, sizeof(meter_urb)); kcontrol->private_value = 0;