linux-kernel - Re: [PATH v4] itimers: Remove bogus NULL pointer check in sys

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Date:	Mon, 22 Jul 2013 10:45:21 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATH v4] itimers: Remove bogus NULL pointer check in sys_getitimer()

Hello Maintainers:

Please help check this patch, when you have time.

Thanks.

On 07/05/2013 09:28 AM, Chen Gang wrote:
> Hello Maintainers:
> 
> Is this patch under the normal work flow (or I should need a little more
> patience) ?
> 
> Thanks.
> 
> On 06/25/2013 09:16 AM, Chen Gang wrote:
>> People might be tricked into assuming that the return value for a
>> failed NULL pointer check should be -EINVAL instead of -EFAULT.
>>
>> Remove the misleading NULL pointer check to fix this nuisance.
>>
>> Aside of that this patch fixes the problem of NOMMU kernels, where
>> a NULL pointer dereference is a valid operation. This allows to
>> boot NOMMU kernels without working around the shortcomings of the
>> getitimer() system call, which have been ignored since this NULL
>> pointer check was introduced in Linux 0.96a.
>>
>> Signed-off-by: Chen Gang <gang.chen@...anux.com>
>> ---
>>  kernel/itimer.c |   13 ++++++-------
>>  1 files changed, 6 insertions(+), 7 deletions(-)
>>
>> diff --git a/kernel/itimer.c b/kernel/itimer.c
>> index 8d262b4..3b12271 100644
>> --- a/kernel/itimer.c
>> +++ b/kernel/itimer.c
>> @@ -102,15 +102,14 @@ int do_getitimer(int which, struct itimerval *value)
>>  
>>  SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
>>  {
>> -	int error = -EFAULT;
>> +	int error;
>>  	struct itimerval get_buffer;
>>  
>> -	if (value) {
>> -		error = do_getitimer(which, &get_buffer);
>> -		if (!error &&
>> -		    copy_to_user(value, &get_buffer, sizeof(get_buffer)))
>> -			error = -EFAULT;
>> -	}
>> +	error = do_getitimer(which, &get_buffer);
>> +	if (!error &&
>> +	    copy_to_user(value, &get_buffer, sizeof(get_buffer)))
>> +		error = -EFAULT;
>> +
>>  	return error;
>>  }
>>  
>>
> 
> 


-- 
Chen Gang
--
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