Re: [PATCH] ALSA: usb-audio: Clamp frame size in implicit-feedback mode

[Takashi Iwai]

On Tue, 28 Jul 2026 22:24:32 +0200,
Sonali Pradhan wrote:
> 
> snd_usb_handle_sync_urb() scales received sync packet sizes by the sender's
> stride and stores the result directly in out_packet->packet_size[i]. If a
> connected USB device sends an oversized sync packet, this frame count can
> exceed ep->maxframesize.
> 
> The un-clamped frame count then propagates to the playback endpoint queue,
> potentially driving packet transfers beyond the endpoint's hardware frame
> limits.
> 
> Cap the calculated frame count against ep->maxframesize in
> snd_usb_handle_sync_urb() to prevent oversized packets from entering the
> playback queue.
> 
> Fixes: 28acb12014fb ("ALSA: usb-audio: use sender stride for implicit feedback")
> Cc: stable@xxxxxxxxxxxxxxx
> Assisted-by: Jetski:Gemini-3.6-Flash
> Signed-off-by: Sonali Pradhan <sonalipradhan@xxxxxxxxxx>

Applied now.  Thanks.


Takashi