Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751861AbaDASyb (ORCPT ); Tue, 1 Apr 2014 14:54:31 -0400 Received: from smtp.bbn.com ([128.33.0.80]:49409 "EHLO smtp.bbn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751763AbaDASy0 (ORCPT ); Tue, 1 Apr 2014 14:54:26 -0400 X-Greylist: delayed 1716 seconds by postgrey-1.27 at vger.kernel.org; Tue, 01 Apr 2014 14:54:26 EDT X-Submitted: to socket.bbn.com (Postfix) with ESMTPSA id 85A69401AE Message-ID: <533B04A9.6090405@bbn.com> Date: Tue, 01 Apr 2014 14:25:45 -0400 From: Richard Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: linux-mm@kvack.org, linux-kernel@vger.kernel.org CC: linux-api@vger.kernel.org, Greg Troxel Subject: [PATCH] mm: msync: require either MS_ASYNC or MS_SYNC X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For the flags parameter, POSIX says "Either MS_ASYNC or MS_SYNC shall be specified, but not both." [1] There was already a test for the "both" condition. Add a test to ensure that the caller specified one of the flags; fail with EINVAL if neither are specified. Without this change, specifying neither is the same as specifying flags=MS_ASYNC because nothing in msync() is conditioned on the MS_ASYNC flag. This has not always been true, and there's no good reason to believe that this behavior would have persisted indefinitely. The msync(2) man page (as currently written in man-pages.git) is silent on the behavior if both flags are unset, so this change should not break an application written by somone who carefully reads the Linux man pages or the POSIX spec. [1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/msync.html Signed-off-by: Richard Hansen Reported-by: Greg Troxel Reviewed-by: Greg Troxel --- This is a resend of: http://article.gmane.org/gmane.linux.kernel/1554416 I didn't get any feedback from that submission, so I'm resending it without changes. mm/msync.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/msync.c b/mm/msync.c index 632df45..472ad3e 100644 --- a/mm/msync.c +++ b/mm/msync.c @@ -42,6 +42,8 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags) goto out; if ((flags & MS_ASYNC) && (flags & MS_SYNC)) goto out; + if (!(flags & (MS_ASYNC | MS_SYNC))) + goto out; error = -ENOMEM; len = (len + ~PAGE_MASK) & PAGE_MASK; end = start + len; -- 1.8.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/