linux-kernel - Re: [PATCH 1/2] prctl: Add PR_SET

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Message-ID: <CAKgNAkjMpjmKCD3oQa7qTeH5gXydDgMj5TjmKKtyXYzV9f--fA@mail.gmail.com>
Date:	Sun, 15 Apr 2012 22:13:51 +1200
From:	"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
To:	Cyrill Gorcunov <gorcunov@...nvz.org>
Cc:	Pavel Emelyanov <xemul@...allels.com>, linux-man@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>, Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 1/2] prctl: Add PR_SET_MM option description

On Sun, Apr 15, 2012 at 6:54 PM, Cyrill Gorcunov <gorcunov@...nvz.org> wrote:
> On Sun, Apr 15, 2012 at 03:48:18PM +1200, Michael Kerrisk (man-pages) wrote:
>> Cyrill,
>>
>> While reviewing your patch to the prctl() manual page, I noticed the
>> following code inkernel/sys.c::prctl_set_mm():
>>
>>         if (opt != PR_SET_MM_START_BRK && opt != PR_SET_MM_BRK) {
>>                 /* It must be existing VMA */
>>                 if (!vma || vma->vm_start > addr)
>>                         goto out;
>>         }
>>
>> At this point, the code causes an exit with error set to zero (i.e.,
>> success). This looks unintended to me. Is the code correct? I suspect
>> a return of -EFAULT or -ENOMEM is warranted.
>
> Hi Michael, yup, -EINVAL escaped (I think EFAULT or ENOMEM is not really
> good here). I'll fix and send update. Thanks!

For what it's worth (I am no expert), it looks to me as though EFAULT
or ENOMEM is more usual after a failed find_vma(). Furthermore, EINVAL
is already heavily used, so not very informative as an error.

Cheers,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface"; http://man7.org/tlpi/
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