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

Laurent Pinchart
2019-04-02T11:33:52Z

Hi Jungo,

Thank you for the patch.

On Tue, Apr 02, 2019 at 06:04:04PM +0800, Jungo Lin wrote:
> From: Jungo Lin <jungo.lin@mediatek.corp-partner.google.com>
>
> 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 <jungo.lin@mediatek.com>
> ---
> 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