The buffer length check before calling uvc_parse_format() only ensured
that the buffer has at least 3 bytes (buflen > 2), buf the function
accesses buffer[3], requiring at least 4 bytes.

This can lead to an out-of-bounds read if the buffer has exactly 3 bytes.

Fix it by checking that the buffer has at least 4 bytes in
uvc_parse_format().

Signed-off-by: Youngjun Lee <yjjuny.lee@samsung.com>
Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/media/usb/uvc/uvc_driver.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index da24a655ab68..1100469a83a2 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -344,6 +344,9 @@ static int uvc_parse_format(struct uvc_device *dev,
 	u8 ftype;
 	int ret;
 
+	if (buflen < 4)
+		return -EINVAL;
+
 	format->type = buffer[2];
 	format->index = buffer[3];
 	format->frames = frames;
-- 
2.43.0