Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows that,
in the worst scenario, could lead to heap overflows.

Also, address the following sparse warnings:
drivers/media/usb/pwc/pwc-uncompress.c:44:44: warning: using sizeof on a flexible structure

Link: https://github.com/KSPP/linux/issues/174
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/media/usb/pwc/pwc-uncompress.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/usb/pwc/pwc-uncompress.c b/drivers/media/usb/pwc/pwc-uncompress.c
index 68bc3829c6b3..faf44cdeb268 100644
--- a/drivers/media/usb/pwc/pwc-uncompress.c
+++ b/drivers/media/usb/pwc/pwc-uncompress.c
@@ -41,7 +41,7 @@ int pwc_decompress(struct pwc_device *pdev, struct pwc_frame_buf *fbuf)
 		memcpy(raw_frame->cmd, pdev->cmd_buf, 4);
 		memcpy(raw_frame+1, yuv, pdev->frame_size);
 		vb2_set_plane_payload(&fbuf->vb.vb2_buf, 0,
-			pdev->frame_size + sizeof(struct pwc_raw_frame));
+			struct_size(raw_frame, rawframe, pdev->frame_size));
 		return 0;
 	}
 
-- 
2.27.0

On Thu, Jan 20, 2022 at 03:24:34PM -0600, Gustavo A. R. Silva wrote:
> Make use of the struct_size() helper instead of an open-coded version,
> in order to avoid any potential type mistakes or integer overflows that,
> in the worst scenario, could lead to heap overflows.
> 
> Also, address the following sparse warnings:
> drivers/media/usb/pwc/pwc-uncompress.c:44:44: warning: using sizeof on a flexible structure
> 
> Link: https://github.com/KSPP/linux/issues/174
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Yup, happy to see these getting changed.

Reviewed-by: Kees Cook <keescook@chromium.org>

> ---
>  drivers/media/usb/pwc/pwc-uncompress.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/usb/pwc/pwc-uncompress.c b/drivers/media/usb/pwc/pwc-uncompress.c
> index 68bc3829c6b3..faf44cdeb268 100644
> --- a/drivers/media/usb/pwc/pwc-uncompress.c
> +++ b/drivers/media/usb/pwc/pwc-uncompress.c
> @@ -41,7 +41,7 @@ int pwc_decompress(struct pwc_device *pdev, struct pwc_frame_buf *fbuf)
>  		memcpy(raw_frame->cmd, pdev->cmd_buf, 4);
>  		memcpy(raw_frame+1, yuv, pdev->frame_size);
>  		vb2_set_plane_payload(&fbuf->vb.vb2_buf, 0,
> -			pdev->frame_size + sizeof(struct pwc_raw_frame));
> +			struct_size(raw_frame, rawframe, pdev->frame_size));
>  		return 0;
>  	}
>  
> -- 
> 2.27.0
> 

-- 
Kees Cook