From patchwork Fri Oct 20 11:07:56 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Reshetova, Elena" X-Patchwork-Id: 10019859 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D9773602CB for ; Fri, 20 Oct 2017 11:16:05 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CE9D028EAA for ; Fri, 20 Oct 2017 11:16:05 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C38B228EAB; Fri, 20 Oct 2017 11:16:05 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 68AE128EB0 for ; Fri, 20 Oct 2017 11:16:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753088AbdJTLQD (ORCPT ); Fri, 20 Oct 2017 07:16:03 -0400 Received: from mga09.intel.com ([134.134.136.24]:35826 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753075AbdJTLQC (ORCPT ); Fri, 20 Oct 2017 07:16:02 -0400 Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Oct 2017 04:16:01 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,405,1503385200"; d="scan'208";a="1208012346" Received: from elena-thinkpad-x230.fi.intel.com ([10.237.72.87]) by fmsmga001.fm.intel.com with ESMTP; 20 Oct 2017 04:15:59 -0700 From: Elena Reshetova To: darrick.wong@oracle.com Cc: linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, peterz@infradead.org, keescook@chromium.org, Elena Reshetova Subject: [PATCH 3/5] fs, xfs: convert xlog_ticket.t_ref from atomic_t to refcount_t Date: Fri, 20 Oct 2017 14:07:56 +0300 Message-Id: <1508497678-10508-4-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1508497678-10508-1-git-send-email-elena.reshetova@intel.com> References: <1508497678-10508-1-git-send-email-elena.reshetova@intel.com> Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable xlog_ticket.t_ref is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook Reviewed-by: David Windsor Reviewed-by: Hans Liljestrand Signed-off-by: Elena Reshetova --- fs/xfs/xfs_log.c | 10 +++++----- fs/xfs/xfs_log_priv.h | 2 +- 2 files changed, 6 insertions(+), 6 deletions(-) diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index dc95a49..e4578c0 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -3571,8 +3571,8 @@ void xfs_log_ticket_put( xlog_ticket_t *ticket) { - ASSERT(atomic_read(&ticket->t_ref) > 0); - if (atomic_dec_and_test(&ticket->t_ref)) + ASSERT(refcount_read(&ticket->t_ref) > 0); + if (refcount_dec_and_test(&ticket->t_ref)) kmem_zone_free(xfs_log_ticket_zone, ticket); } @@ -3580,8 +3580,8 @@ xlog_ticket_t * xfs_log_ticket_get( xlog_ticket_t *ticket) { - ASSERT(atomic_read(&ticket->t_ref) > 0); - atomic_inc(&ticket->t_ref); + ASSERT(refcount_read(&ticket->t_ref) > 0); + refcount_inc(&ticket->t_ref); return ticket; } @@ -3703,7 +3703,7 @@ xlog_ticket_alloc( unit_res = xfs_log_calc_unit_res(log->l_mp, unit_bytes); - atomic_set(&tic->t_ref, 1); + refcount_set(&tic->t_ref, 1); tic->t_task = current; INIT_LIST_HEAD(&tic->t_queue); tic->t_unit_res = unit_res; diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h index 51bf7b8..29f6e1f 100644 --- a/fs/xfs/xfs_log_priv.h +++ b/fs/xfs/xfs_log_priv.h @@ -168,7 +168,7 @@ typedef struct xlog_ticket { struct list_head t_queue; /* reserve/write queue */ struct task_struct *t_task; /* task that owns this ticket */ xlog_tid_t t_tid; /* transaction identifier : 4 */ - atomic_t t_ref; /* ticket reference count : 4 */ + refcount_t t_ref; /* ticket reference count : 4 */ int t_curr_res; /* current reservation in bytes : 4 */ int t_unit_res; /* unit reservation in bytes : 4 */ char t_ocnt; /* original count : 1 */