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ALSA: usb-audio: Clamp frame size in implicit-feedback mode

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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: 28acb12014 ("ALSA: usb-audio: use sender stride for implicit feedback")
Cc: stable@vger.kernel.org
Assisted-by: Jetski:Gemini-3.6-Flash
Signed-off-by: Sonali Pradhan <sonalipradhan@google.com>
Link: https://patch.msgid.link/20260728202432.2354994-1-sonalipradhan@google.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Sonali Pradhan 2026-07-28 20:24:32 +00:00 committed by Takashi Iwai
parent d0199ae166
commit 8d7a30c50c
1 changed files with 5 additions and 3 deletions
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8
sound/usb/endpoint.c
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@ -1819,11 +1819,13 @@ static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
out_packet->packets = in_ctx->packets;
for (i = 0; i < in_ctx->packets; i++) {
if (urb->iso_frame_desc[i].status == 0)
out_packet->packet_size[i] =
if (urb->iso_frame_desc[i].status == 0) {
unsigned int frames =
urb->iso_frame_desc[i].actual_length / sender->stride;
else
out_packet->packet_size[i] = min(frames, ep->maxframesize);
} else {
out_packet->packet_size[i] = 0;
}
}
spin_unlock_irqrestore(&ep->lock, flags);