Commit aed97647 authored Oct 09, 2012 by Richard W.M. Jones Committed by Al Viro Oct 09, 2012

dup3: Return an error when oldfd == newfd.

I have tested the attached patch to fix the dup3 regression.

Rich.

From 0944e30e12dec6544b3602626b60ff412375c78f Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Tue, 9 Oct 2012 14:42:45 +0100
Subject: [PATCH] dup3: Return an error when oldfd == newfd.

The following commit:

  commit fe17f22d
  Author: Al Viro <viro@zeniv.linux.org.uk>
  Date:   Tue Aug 21 11:48:11 2012 -0400

    take purely descriptor-related stuff from fcntl.c to file.c

was supposed to be just code motion, but it dropped the following two
lines:

  if (unlikely(oldfd == newfd))
          return -EINVAL;

from the dup3 system call.  dup3 is not specified by POSIX, so Linux
can do what it likes.  However the POSIX proposal for dup3 [1] states
that it should return an error if oldfd == newfd.

[1] http://austingroupbugs.net/view.php?id=411

Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent d1c7d97a

fs/file.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -922,6 +922,9 @@ SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags)
		if ((flags & ~O_CLOEXEC) != 0)
		return -EINVAL;

		if (unlikely(oldfd == newfd))
		return -EINVAL;

		if (newfd >= rlimit(RLIMIT_NOFILE))
		return -EMFILE;

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