Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754989Ab3JUI7p (ORCPT ); Mon, 21 Oct 2013 04:59:45 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:39861 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754527Ab3JUIxS (ORCPT ); Mon, 21 Oct 2013 04:53:18 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Li Zefan" , "Tejun Heo" , "Kirill A. Shutemov" Date: Mon, 21 Oct 2013 09:46:28 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 131/149] cgroup: fail if monitored file and event_control are in different cgroup In-Reply-To: X-SA-Exim-Connect-IP: 212.20.242.100 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1678 Lines: 57 3.2.52-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Li Zefan commit f169007b2773f285e098cb84c74aac0154d65ff7 upstream. If we pass fd of memory.usage_in_bytes of cgroup A to cgroup.event_control of cgroup B, then we won't get memory usage notification from A but B! What's worse, if A and B are in different mount hierarchy, we'll end up accessing NULL pointer! Disallow this kind of invalid usage. Signed-off-by: Li Zefan Acked-by: Kirill A. Shutemov Signed-off-by: Tejun Heo Signed-off-by: Ben Hutchings --- kernel/cgroup.c | 11 +++++++++++ 1 file changed, 11 insertions(+) --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3504,6 +3504,7 @@ static int cgroup_write_event_control(st const char *buffer) { struct cgroup_event *event = NULL; + struct cgroup *cgrp_cfile; unsigned int efd, cfd; struct file *efile = NULL; struct file *cfile = NULL; @@ -3559,6 +3560,16 @@ static int cgroup_write_event_control(st goto fail; } + /* + * The file to be monitored must be in the same cgroup as + * cgroup.event_control is. + */ + cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent); + if (cgrp_cfile != cgrp) { + ret = -EINVAL; + goto fail; + } + if (!event->cft->register_event || !event->cft->unregister_event) { ret = -EINVAL; goto fail; -- 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/