5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: HyeongJun An <redacted>
commit e4637ce34607f1733a34a57294966d26b263e626 upstream.
The snd_usbmidi_us122l_output() picks a count of 2 on anything slower
than high speed and never relates it to ep->max_transfer. The URB
buffer holds exactly max_transfer bytes, so a device declaring a one
byte bulk endpoint takes two bytes from snd_rawmidi_transmit(), and the
memset that pads the rest computes 1 - 2 in int and wraps to SIZE_MAX.
Only 0x800e and 0x800f are pinned to nine bytes. The US-122MKII at
0x0644:0x8021 falls to the default and takes usb_maxpacket(), which the
USB core only clamps downward.
The akai and novation output ops in this file were given the same guard
recently. Do the same here.
Fixes: 030a07e44129 ("ALSA: Add USB US122L driver")
Cc: <redacted>
Assisted-by: Claude:claude-opus-5
Signed-off-by: HyeongJun An <redacted>
Link: https://patch.msgid.link/20260901090409.1478573-1-sammiee5311@gmail.com (local)
Signed-off-by: Takashi Iwai <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
sound/usb/midi.c | 2 ++
1 file changed, 2 insertions(+)
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -974,6 +974,8 @@ static void snd_usbmidi_us122l_output(st
default:
count = 2;
}
+ if (ep->max_transfer < count)
+ return;
count = snd_rawmidi_transmit(ep->ports[0].substream,
urb->transfer_buffer,
count);