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Commit 64188cfb authored by Takashi Iwai's avatar Takashi Iwai
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Revert "ALSA: usb-audio: purge needless variable length array" 

This reverts commit 89b593c3 ("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: 89b593c3 ("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: default avatarTakashi Iwai <tiwai@suse.de>
parent 1fc2e41f

sound/usb/mixer_us16x08.c

+4 −4
Original line number Diff line number Diff line
@@ -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;