From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757967AbZEKSpO (ORCPT ); Mon, 11 May 2009 14:45:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753084AbZEKSo6 (ORCPT ); Mon, 11 May 2009 14:44:58 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:43326 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751392AbZEKSo6 (ORCPT ); Mon, 11 May 2009 14:44:58 -0400 Date: Mon, 11 May 2009 11:40:56 -0700 (PDT) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: Jeff Mahoney cc: Andrew Morton , Linux Kernel Mailing List , Al Viro Subject: Re: [PATCH] dup2: Fix return value with oldfd == newfd and invalid fd In-Reply-To: <4A086D9E.60308@suse.com> Message-ID: References: <4A086D9E.60308@suse.com> User-Agent: Alpine 2.01 (LFD 1184 2008-12-16) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 11 May 2009, Jeff Mahoney wrote: > > The return value of dup2 when oldfd == newfd and the fd isn't valid is not > getting properly sign extended. We end up with 4294967287 instead of -EBADF. Indeed. > This patch uses a signed int for the error value so it is properly extended. However, I'd rather move the new variable into the block where it is used, and keep the whole corner-case thing self-contained. So can you verify that this trivial variation on the patch is ok by you, and I'll commit it as yours with your message? (I realize it's really trivial, and I could just do this myself, but good to get the change ack'ed anyway). Linus --- fs/fcntl.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/fcntl.c b/fs/fcntl.c index cc8e4de..1ad7031 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -117,11 +117,13 @@ SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd) { if (unlikely(newfd == oldfd)) { /* corner case */ struct files_struct *files = current->files; + int retval = oldfd; + rcu_read_lock(); if (!fcheck_files(files, oldfd)) - oldfd = -EBADF; + retval = -EBADF; rcu_read_unlock(); - return oldfd; + return retval; } return sys_dup3(oldfd, newfd, 0); }