Re: [PATCH] ALSA: usb-audio: fix OOB write in snd_usbmidi_us122l_output()

[Takashi Iwai]

On Tue, 01 Sep 2026 11:04:09 +0200,
HyeongJun An wrote:
> 
> 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: stable@xxxxxxxxxxxxxxx
> Assisted-by: Claude:claude-opus-5
> Signed-off-by: HyeongJun An <sammiee5311@xxxxxxxxx>

Applied now.  Thanks.


Takashi