Re: [PATCH] Prevent buffer overflow in UVC Gadget setup handler

From: Dan Scally
Date: Thu Dec 01 2022 - 08:49:53 EST


Hello - thanks for the patch

On 01/12/2022 12:21, Szymon Heidrich wrote:
Setup function uvc_function_setup


You've written uvc_function_setup here, but the code changes uvc_function_ep0_complete.

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@xxxxxxxxx>


Good catch

---
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);


There's a clamp() macro in f_uvc.c, can we use that?

+ memcpy(&uvc_event->data.data, req->buf, uvc_event->data.length);
v4l2_event_queue(&uvc->vdev, &v4l2_event);
}
}