Commit 40d3ac25 authored by Ricardo Ribalda's avatar Ricardo Ribalda Committed by Hans Verkuil
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media: uvcvideo: Fix allocation for small frame sizes 



If a frame has size of less or equal than one packet size
uvc_alloc_urb_buffers() is unable to allocate memory for it due to a
off-by-one error.

Fix the off-by-one-error and now that we are at it, make sure that
stream->urb_size has always a valid value when we return from the
function, even when an error happens.

Fixes: efdc8a95 ("V4L/DVB (10295): uvcvideo: Retry URB buffers allocation when the system is low on memory.")
Reported-by: default avatarItay Chamiel <itay.chamiel@q.ai>
Closes: https://lore.kernel.org/linux-media/CANiDSCsSoZf2LsCCoWAUbCg6tJT-ypXR1B85aa6rAdMVYr2iBQ@mail.gmail.com/T/#t


Co-developed-by: default avatarItay Chamiel <itay.chamiel@q.ai>
Signed-off-by: default avatarItay Chamiel <itay.chamiel@q.ai>
Signed-off-by: default avatarRicardo Ribalda <ribalda@chromium.org>
Reviewed-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: default avatarItay Chamiel <itay.chamiel@q.ai>
Link: https://patch.msgid.link/20260114-uvc-alloc-urb-v1-1-cedf3fb66711@chromium.org


Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarHans Verkuil <hverkuil+cisco@kernel.org>
parent 4cf3b6fd

drivers/media/usb/uvc/uvc_video.c

+2 −1
Original line number Diff line number Diff line
@@ -1812,7 +1812,7 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream, 
		npackets = UVC_MAX_PACKETS;



	/* Retry allocations until one succeed. */

	for (; npackets > 1; npackets /= 2) {

	for (; npackets > 0; npackets /= 2) {

		stream->urb_size = psize * npackets;



		for (i = 0; i < UVC_URBS; ++i) {
@@ -1837,6 +1837,7 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream, 
	uvc_dbg(stream->dev, VIDEO,

		"Failed to allocate URB buffers (%u bytes per packet)\n",

		psize);

	stream->urb_size = 0;

	return 0;

}