linux-kernel - [PATCH] Prevent buffer overflow in UVC Gadget setup handler

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Message-Id: <20221201122141.8739-1-szymon.heidrich@gmail.com>
Date:   Thu,  1 Dec 2022 13:21:41 +0100
From:   Szymon Heidrich <szymon.heidrich@...il.com>
To:     laurent.pinchart@...asonboard.com
Cc:     szymon.heidrich@...il.com, Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] Prevent buffer overflow in UVC Gadget setup handler

Setup function uvc_function_setup permits control transfer
requests with up to 64 bytes of payload (UVC_MAX_REQUEST_SIZE),
data stage handler for OUT transfer uses memcpy to copy req->actual
bytes to uvc_event->data.data array of size 60. This may result
in an overflow of 4 bytes.

Signed-off-by: Szymon Heidrich <szymon.heidrich@...il.com>
---
 drivers/usb/gadget/function/f_uvc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index 6e196e061..69c5eb3a3 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -216,8 +216,9 @@ uvc_function_ep0_complete(struct usb_ep *ep, struct usb_request *req)
 
 		memset(&v4l2_event, 0, sizeof(v4l2_event));
 		v4l2_event.type = UVC_EVENT_DATA;
-		uvc_event->data.length = req->actual;
-		memcpy(&uvc_event->data.data, req->buf, req->actual);
+		uvc_event->data.length = (req->actual > sizeof(uvc_event->data.data) ?
+			sizeof(uvc_event->data.data) : req->actual);
+		memcpy(&uvc_event->data.data, req->buf, uvc_event->data.length);
 		v4l2_event_queue(&uvc->vdev, &v4l2_event);
 	}
 }
-- 
2.38.1