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Revert "ALSA: usb-audio: purge needless variable length array"

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This reverts commit 89b593c30e ("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: 89b593c30e ("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>
This commit is contained in:
Takashi Iwai 2017-05-30 09:23:41 +02:00
parent 1fc2e41f7a
commit 64188cfbe5
1 changed files with 4 additions and 4 deletions
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8
sound/usb/mixer_us16x08.c
View file

@ -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;