Subject: Re: [PATCH v1] media: media_device_enum_links32: fix missing reserved field copy

From: Laurent Pinchart <[email-masked]>
Date: Tue, 2 Apr 2019 14:33:39 +0300

Hi Jungo,

Thank you for the patch.

On Tue, Apr 02, 2019 at 06:04:04PM +0800, Jungo Lin wrote:
> From: Jungo Lin <[email-masked]>
> 
> In v4l2-compliance utility, test MEDIA_IOC_ENUM_ENTITIES
> will check whether reserved field of media_links_enum filled
> with zero. Reserved field is filled with zero in media_device_enum_links.
> 
> However, for 32 bit program, the reserved field is missing
> copy from kernel space to user space in media_device_enum_links32
> function.
> 
> This patch copies reserved field of media_links_enum from kernel space
> to user space.
> 
> Signed-off-by: Jungo Lin <[email-masked]>
> ---
>  drivers/media/media-device.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
> index b8ec886..f420829 100644
> --- a/drivers/media/media-device.c
> +++ b/drivers/media/media-device.c
> @@ -502,6 +502,7 @@ static long media_device_enum_links32(struct media_device *mdev,
>  {
>  	struct media_links_enum links;
>  	compat_uptr_t pads_ptr, links_ptr;
> +	int ret;
>  
>  	memset(&links, 0, sizeof(links));
>  
> @@ -513,7 +514,15 @@ static long media_device_enum_links32(struct media_device *mdev,
>  	links.pads = compat_ptr(pads_ptr);
>  	links.links = compat_ptr(links_ptr);
>  
> -	return media_device_enum_links(mdev, &links);
> +	ret = media_device_enum_links(mdev, &links);
> +	if (ret)
> +		return ret;
> +
> +	if (copy_to_user(ulinks->reserved, &links.reserved,
> +			 sizeof(links.reserved)))
> +		return -EFAULT;

I think it would be better to zero the reserved field here instead of
copying it, as we know it has to be zero.

> +
> +	return 0;
>  }
>  
>  #define MEDIA_IOC_ENUM_LINKS32		_IOWR('|', 0x02, struct media_links_enum32)

-- 
Regards,

Laurent Pinchart

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