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Subject: Re: [PATCH] s390: crypto: Return -EFAULT if copy_to_user() fails
To:     Wang Qing <wangqing@vivo.com>, Pierre Morel <pmorel@linux.ibm.com>,
        Halil Pasic <pasic@linux.ibm.com>,
        Harald Freudenberger <freude@linux.ibm.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1614600502-16714-1-git-send-email-wangqing@vivo.com>
From:   Tony Krowiak <akrowiak@linux.ibm.com>
Message-ID: <ffe84ace-92db-c7f5-7e66-fe3172484ec6@linux.ibm.com>
Date:   Mon, 1 Mar 2021 07:18:20 -0500
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On 3/1/21 7:08 AM, Wang Qing wrote:
> The copy_to_user() function returns the number of bytes remaining to be
> copied, but we want to return -EFAULT if the copy doesn't complete.
>
> Signed-off-by: Wang Qing <wangqing@vivo.com>
> ---
>   drivers/s390/crypto/vfio_ap_ops.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 41fc2e413..1ffdd41
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -1286,7 +1286,7 @@ static int vfio_ap_mdev_get_device_info(unsigned long arg)
>   	info.num_regions = 0;
>   	info.num_irqs = 0;
>   
> -	return copy_to_user((void __user *)arg, &info, minsz);
> +	return copy_to_user((void __user *)arg, &info, minsz) ? -EFAULT : 0;
>   }

LGTM
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>

>   
>   static ssize_t vfio_ap_mdev_ioctl(struct mdev_device *mdev,