media: uvcvideo: Do not mark valid metadata as invalid

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>

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 11769a1832d2ba9b3f9a50bcb10b0c4cdff71f09..2e377e7b9e81599aca19b800a171cc16a09c1e8a 100644 (file)
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1442,12 +1442,6 @@ 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;
 
@@ -1468,6 +1462,12 @@ 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();