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

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Date:	Fri, 05 Jul 2013 09:28:39 +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:

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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