From patchwork Thu Mar 2 10:43:08 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Reshetova, Elena" X-Patchwork-Id: 9599979 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 19D4B60414 for ; Thu, 2 Mar 2017 10:47:15 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EE68B285A7 for ; Thu, 2 Mar 2017 10:47:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E2F15285AE; Thu, 2 Mar 2017 10:47:14 +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=unavailable 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 973A3285A7 for ; Thu, 2 Mar 2017 10:47:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751900AbdCBKop (ORCPT ); Thu, 2 Mar 2017 05:44:45 -0500 Received: from mga07.intel.com ([134.134.136.100]:4745 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750779AbdCBKoN (ORCPT ); Thu, 2 Mar 2017 05:44:13 -0500 Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga105.jf.intel.com with ESMTP; 02 Mar 2017 02:43:30 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.35,230,1484035200"; d="scan'208";a="231414677" Received: from bheise-mobl.ger.corp.intel.com (HELO elena-ThinkPad-X230.ger.corp.intel.com) ([10.249.41.240]) by fmsmga004.fm.intel.com with ESMTP; 02 Mar 2017 02:43:24 -0800 From: Elena Reshetova To: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-nilfs@vger.kernel.org, linux-cachefs@redhat.com, linux-cifs@vger.kernel.org, peterz@infradead.org, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk, dhowells@redhat.com, sfrench@samba.org, eparis@parisplace.org, konishi.ryusuke@lab.ntt.co.jp, john@johnmccutchan.com, rlove@rlove.org, paul@paul-moore.com, Elena Reshetova , Hans Liljestrand , Kees Cook , David Windsor Subject: [PATCH 01/10] fs, kernfs: convert kernfs_node.count from atomic_t to refcount_t Date: Thu, 2 Mar 2017 12:43:08 +0200 Message-Id: <1488451397-3365-2-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1488451397-3365-1-git-send-email-elena.reshetova@intel.com> References: <1488451397-3365-1-git-send-email-elena.reshetova@intel.com> Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Signed-off-by: Elena Reshetova Signed-off-by: Hans Liljestrand Signed-off-by: Kees Cook Signed-off-by: David Windsor --- fs/kernfs/dir.c | 12 +++++------- include/linux/kernfs.h | 3 ++- 2 files changed, 7 insertions(+), 8 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index db5900aaa..2a07de1 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -489,10 +489,8 @@ static void kernfs_drain(struct kernfs_node *kn) */ void kernfs_get(struct kernfs_node *kn) { - if (kn) { - WARN_ON(!atomic_read(&kn->count)); - atomic_inc(&kn->count); - } + if (kn) + refcount_inc(&kn->count); } EXPORT_SYMBOL_GPL(kernfs_get); @@ -507,7 +505,7 @@ void kernfs_put(struct kernfs_node *kn) struct kernfs_node *parent; struct kernfs_root *root; - if (!kn || !atomic_dec_and_test(&kn->count)) + if (!kn || !refcount_dec_and_test(&kn->count)) return; root = kernfs_root(kn); repeat: @@ -538,7 +536,7 @@ void kernfs_put(struct kernfs_node *kn) kn = parent; if (kn) { - if (atomic_dec_and_test(&kn->count)) + if (refcount_dec_and_test(&kn->count)) goto repeat; } else { /* just released the root kn, free @root too */ @@ -635,7 +633,7 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, goto err_out2; kn->ino = ret; - atomic_set(&kn->count, 1); + refcount_set(&kn->count, 1); atomic_set(&kn->active, KN_DEACTIVATED_BIAS); RB_CLEAR_NODE(&kn->rb); diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index a9b11b8..baabbaf 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -15,6 +15,7 @@ #include #include #include +#include #include struct file; @@ -105,7 +106,7 @@ struct kernfs_elem_attr { * active reference. */ struct kernfs_node { - atomic_t count; + refcount_t count; atomic_t active; #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map;