[PATCH 6.1 11/55] media: uvcvideo: Use heuristic to find stream entity

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ricardo Ribalda <ribalda@chromium.org>

[ Upstream commit 758dbc756aad429da11c569c0d067f7fd032bcf7 ]

Some devices, like the Grandstream GUV3100 webcam, have an invalid UVC
descriptor where multiple entities share the same ID, this is invalid
and makes it impossible to make a proper entity tree without heuristics.

We have recently introduced a change in the way that we handle invalid
entities that has caused a regression on broken devices.

Implement a new heuristic to handle these devices properly.

Reported-by: Angel4005 <ooara1337@gmail.com>
Closes: https://lore.kernel.org/linux-media/CAOzBiVuS7ygUjjhCbyWg-KiNx+HFTYnqH5+GJhd6cYsNLT=DaA@mail.gmail.com/
Fixes: 0e2ee70291e6 ("media: uvcvideo: Mark invalid entities with id UVC_INVALID_ENTITY_ID")
Cc: stable@vger.kernel.org
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index f81bddd20bc09..a1c6ae97a2b93 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -164,13 +164,26 @@ static struct uvc_entity *uvc_entity_by_reference(struct uvc_device *dev,
 
 static struct uvc_streaming *uvc_stream_by_id(struct uvc_device *dev, int id)
 {
-	struct uvc_streaming *stream;
+	struct uvc_streaming *stream, *last_stream;
+	unsigned int count = 0;
 
 	list_for_each_entry(stream, &dev->streams, list) {
+		count += 1;
+		last_stream = stream;
 		if (stream->header.bTerminalLink == id)
 			return stream;
 	}
 
+	/*
+	 * If the streaming entity is referenced by an invalid ID, notify the
+	 * user and use heuristics to guess the correct entity.
+	 */
+	if (count == 1 && id == UVC_INVALID_ENTITY_ID) {
+		dev_warn(&dev->intf->dev,
+			 "UVC non compliance: Invalid USB header. The streaming entity has an invalid ID, guessing the correct one.");
+		return last_stream;
+	}
+
 	return NULL;
 }
 
-- 
2.53.0