linux-kernel - Bad error return after find_vma() in PR_SET

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Message-ID: <CAKgNAkjWdy_SYaJsNXUOv7cNL2xwZNW7FCdRsT6wiRFb0dmetw@mail.gmail.com>
Date:	Sun, 15 Apr 2012 16:00:17 +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>,
	Andrew Morton <akpm@...l.org>,
	Michael Kerrisk <mtk.manpages@...il.com>
Subject: Bad error return after find_vma() in PR_SET_MM code

[Bother! Resending with corrected subject line (was "[PATCH 1/2]
prctl: Add PR_SET_MM option description")]

Cyrill,

While reviewing your patch to the prctl() manual page, I noticed the
following code in kernel/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.

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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