[PATCH] efi_runtime: Use memdup_user helper

[ivanhu]

On 07/03/2017 03:54 PM, Colin Ian King wrote:
> On 03/07/17 08:48, Ivan Hu wrote:
>> From: Geliang Tang <geliangtang at gmail.com>
>>
>> Sync up with kernel driver efi_test:
>>
>> efi/efi_test: Use memdup_user() helper
>>
>> Use memdup_user() helper instead of open-coding to simplify the code.
>>
>> Signed-off-by: Geliang Tang <geliangtang at gmail.com>
>> Signed-off-by: Ivan Hu <ivan.hu at canonical.com>
>> ---
>>   efi_runtime/efi_runtime.c | 11 +++--------
>>   1 file changed, 3 insertions(+), 8 deletions(-)
>>
>> diff --git a/efi_runtime/efi_runtime.c b/efi_runtime/efi_runtime.c
>> index 19b624c..6570a54 100644
>> --- a/efi_runtime/efi_runtime.c
>> +++ b/efi_runtime/efi_runtime.c
>> @@ -90,18 +90,13 @@ copy_ucs2_from_user_len(efi_char16_t **dst, efi_char16_t __user *src,
>>   	if (!access_ok(VERIFY_READ, src, 1))
>>   		return -EFAULT;
>>   
>> -	buf = kmalloc(len, GFP_KERNEL);
>> -	if (!buf) {
>> +	buf = memdup_user(src, len);
>> +	if (IS_ERR(buf)) {
>>   		*dst = NULL;
>> -		return -ENOMEM;
>> +		return PTR_ERR(buf);
>>   	}
>>   	*dst = buf;
>>   
>> -	if (copy_from_user(*dst, src, len)) {
>> -		kfree(buf);
>> -		return -EFAULT;
>> -	}
>> -
>>   	return 0;
>>   }
>>   
>>
> Ivan, this is great for the latest kernel, what do we do for backwards
> compatibility in the fwts DKMS driver?
> 

Colin, memdup_user has introduced for a very long time,since 2009. Looks 
like should not be a problem for the DKMS driver. What backward 
compatibility issue have you seen?

Ivan

> Acked-by: Colin Ian King <colin.king at canonical.com>
>