[v3] usb: gadget: uvc: Prevent buffer overflow in setup handler

[PATCH v3] usb: gadget: uvc: Prevent buffer overflow in setup handler

Posted by Szymon Heidrich 3 years, 2 months ago

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.

Fixes: cdda479f15cd ("USB gadget: video class function driver")
Signed-off-by: Szymon Heidrich <szymon.heidrich@gmail.com>
---
V1 -> V2: Corrected commit message and changed ?: in favor of min_t
V2 -> V3: Added fixes tag

 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..4419b7972 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 = min_t(unsigned int, req->actual,
+			sizeof(uvc_event->data.data));
+		memcpy(&uvc_event->data.data, req->buf, uvc_event->data.length);
 		v4l2_event_queue(&uvc->vdev, &v4l2_event);
 	}
 }
-- 
2.38.1

Re: [PATCH v3] usb: gadget: uvc: Prevent buffer overflow in setup handler

Posted by Laurent Pinchart 3 years, 2 months ago

Hi Szymon,

Thank you for the patch.

On Tue, Dec 06, 2022 at 03:13:01PM +0100, Szymon Heidrich wrote:
> 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.
> 
> Fixes: cdda479f15cd ("USB gadget: video class function driver")
> Signed-off-by: Szymon Heidrich <szymon.heidrich@gmail.com>

Good catch.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
> V1 -> V2: Corrected commit message and changed ?: in favor of min_t
> V2 -> V3: Added fixes tag
> 
>  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..4419b7972 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 = min_t(unsigned int, req->actual,
> +			sizeof(uvc_event->data.data));
> +		memcpy(&uvc_event->data.data, req->buf, uvc_event->data.length);
>  		v4l2_event_queue(&uvc->vdev, &v4l2_event);
>  	}
>  }

-- 
Regards,

Laurent Pinchart

Re: [PATCH v3] usb: gadget: uvc: Prevent buffer overflow in setup handler

Posted by Szymon Heidrich 3 years, 2 months ago

On 06/12/2022 22:21, Laurent Pinchart wrote:
> Hi Szymon,
> 
> Thank you for the patch.
> 
> On Tue, Dec 06, 2022 at 03:13:01PM +0100, Szymon Heidrich wrote:
>> 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.
>>
>> Fixes: cdda479f15cd ("USB gadget: video class function driver")
>> Signed-off-by: Szymon Heidrich <szymon.heidrich@gmail.com>
> 
> Good catch.
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> 
>> ---
>> V1 -> V2: Corrected commit message and changed ?: in favor of min_t
>> V2 -> V3: Added fixes tag
>>
>>  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..4419b7972 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 = min_t(unsigned int, req->actual,
>> +			sizeof(uvc_event->data.data));
>> +		memcpy(&uvc_event->data.data, req->buf, uvc_event->data.length);
>>  		v4l2_event_queue(&uvc->vdev, &v4l2_event);
>>  	}
>>  }
> 

Hello Dan and Laurent,

Thank you very much for your time, review and accurate remarks.

Best regards,
Szymon