media: uvcvideo: Do not mark valid metadata as invalid

commit bda2859bff0b9596a19648f3740c697ce4c71496 upstream.

Currently, the driver performs a length check of the metadata buffer
before the actual metadata size is known and before the metadata is
decided to be copied. This results in valid metadata buffers being
incorrectly marked as invalid.

Move the length check to occur after the metadata size is determined and
is decided to be copied.

Cc: stable@vger.kernel.org
Fixes: 088ead255245 ("media: uvcvideo: Add a metadata device node")
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Link: https://lore.kernel.org/r/20250707-uvc-meta-v8-1-ed17f8b1218b@chromium.org
Signed-off-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 17ec298ee4f7d0e505ef7501e688cfe9eeff4af6..57e6f9af536ff8b7b5bb670e2aec6478c2637fef 100644 (file)
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1437,12 +1437,6 @@ static void uvc_video_decode_meta(struct uvc_streaming *stream,
        if (!meta_buf || length == 2)
                return;
 
-       if (meta_buf->length - meta_buf->bytesused <
-           length + sizeof(meta->ns) + sizeof(meta->sof)) {
-               meta_buf->error = 1;
-               return;
-       }
-
        has_pts = mem[1] & UVC_STREAM_PTS;
        has_scr = mem[1] & UVC_STREAM_SCR;
 
@@ -1463,6 +1457,12 @@ static void uvc_video_decode_meta(struct uvc_streaming *stream,
                                  !memcmp(scr, stream->clock.last_scr, 6)))
                return;
 
+       if (meta_buf->length - meta_buf->bytesused <
+           length + sizeof(meta->ns) + sizeof(meta->sof)) {
+               meta_buf->error = 1;
+               return;
+       }
+
        meta = (struct uvc_meta_buf *)((u8 *)meta_buf->mem + meta_buf->bytesused);
        local_irq_save(flags);
        time = uvc_video_get_time();