From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761402AbZEFUl2 (ORCPT ); Wed, 6 May 2009 16:41:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761096AbZEFUjE (ORCPT ); Wed, 6 May 2009 16:39:04 -0400 Received: from kroah.org ([198.145.64.141]:33902 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761059AbZEFUjD (ORCPT ); Wed, 6 May 2009 16:39:03 -0400 X-Mailbox-Line: From greg@blue.kroah.org Wed May 6 13:31:29 2009 Message-Id: <20090506203129.431125090@blue.kroah.org> User-Agent: quilt/0.48-1 Date: Wed, 06 May 2009 13:30:18 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Vitaly Mayatskikh , Thomas Tuttle , Matt Mackall , Alexey Dobriyan , Greg Kroah-Hartman Subject: [patch 08/18] pagemap: require aligned-length, non-null reads of /proc/pid/pagemap References: <20090506203010.615363711@blue.kroah.org> Content-Disposition: inline; filename=pagemap-require-aligned-length-non-null-reads-of-proc-pid-pagemap.patch In-Reply-To: <20090506203353.GA14624@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Vitaly Mayatskikh commit 0816178638c15ce5472d39d771a96860dff4141a upstream. The intention of commit aae8679b0ebcaa92f99c1c3cb0cd651594a43915 ("pagemap: fix bug in add_to_pagemap, require aligned-length reads of /proc/pid/pagemap") was to force reads of /proc/pid/pagemap to be a multiple of 8 bytes, but now it allows to read 0 bytes, which actually puts some data to user's buffer. According to POSIX, if count is zero, read() should return zero and has no other results. Signed-off-by: Vitaly Mayatskikh Cc: Thomas Tuttle Acked-by: Matt Mackall Cc: Alexey Dobriyan Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/proc/task_mmu.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -665,6 +665,10 @@ static ssize_t pagemap_read(struct file goto out_task; ret = 0; + + if (!count) + goto out_task; + mm = get_task_mm(task); if (!mm) goto out_task;