From patchwork Fri Oct 20 11:07:58 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Reshetova, Elena" X-Patchwork-Id: 10019863 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 83A09602CB for ; Fri, 20 Oct 2017 11:16:08 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 78EAC28EAA for ; Fri, 20 Oct 2017 11:16:08 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6DF7528EB0; Fri, 20 Oct 2017 11:16:08 +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 151BF28EAA for ; Fri, 20 Oct 2017 11:16:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753118AbdJTLQH (ORCPT ); Fri, 20 Oct 2017 07:16:07 -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 S1753053AbdJTLQG (ORCPT ); Fri, 20 Oct 2017 07:16:06 -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 04:16:05 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,405,1503385200"; d="scan'208";a="1208012389" Received: from elena-thinkpad-x230.fi.intel.com ([10.237.72.87]) by fmsmga001.fm.intel.com with ESMTP; 20 Oct 2017 04:16:03 -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 5/5] fs, xfs: convert xfs_rui_log_item.rui_refcount from atomic_t to refcount_t Date: Fri, 20 Oct 2017 14:07:58 +0300 Message-Id: <1508497678-10508-6-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 xfs_rui_log_item.rui_refcount 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_rmap_item.c | 6 +++--- fs/xfs/xfs_rmap_item.h | 2 +- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c index f3b139c..f914829f 100644 --- a/fs/xfs/xfs_rmap_item.c +++ b/fs/xfs/xfs_rmap_item.c @@ -204,7 +204,7 @@ xfs_rui_init( ruip->rui_format.rui_nextents = nextents; ruip->rui_format.rui_id = (uintptr_t)(void *)ruip; atomic_set(&ruip->rui_next_extent, 0); - atomic_set(&ruip->rui_refcount, 2); + refcount_set(&ruip->rui_refcount, 2); return ruip; } @@ -243,8 +243,8 @@ void xfs_rui_release( struct xfs_rui_log_item *ruip) { - ASSERT(atomic_read(&ruip->rui_refcount) > 0); - if (atomic_dec_and_test(&ruip->rui_refcount)) { + ASSERT(refcount_read(&ruip->rui_refcount) > 0); + if (refcount_dec_and_test(&ruip->rui_refcount)) { xfs_trans_ail_remove(&ruip->rui_item, SHUTDOWN_LOG_IO_ERROR); xfs_rui_item_free(ruip); } diff --git a/fs/xfs/xfs_rmap_item.h b/fs/xfs/xfs_rmap_item.h index 340c968..1e425a9 100644 --- a/fs/xfs/xfs_rmap_item.h +++ b/fs/xfs/xfs_rmap_item.h @@ -64,7 +64,7 @@ struct kmem_zone; */ struct xfs_rui_log_item { struct xfs_log_item rui_item; - atomic_t rui_refcount; + refcount_t rui_refcount; atomic_t rui_next_extent; unsigned long rui_flags; /* misc flags */ struct xfs_rui_log_format rui_format;