From patchwork Wed Mar 1 10:42:15 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Reshetova, Elena" X-Patchwork-Id: 9598199 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 7484960429 for ; Wed, 1 Mar 2017 10:46:46 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A51B8284F9 for ; Wed, 1 Mar 2017 10:46:46 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 99FC228504; Wed, 1 Mar 2017 10:46:46 +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=-6.4 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM 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 4CFCA284F5 for ; Wed, 1 Mar 2017 10:46:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752371AbdCAKmv (ORCPT ); Wed, 1 Mar 2017 05:42:51 -0500 Received: from mga02.intel.com ([134.134.136.20]:18613 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751475AbdCAKme (ORCPT ); Wed, 1 Mar 2017 05:42:34 -0500 Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 01 Mar 2017 02:42:33 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.35,225,1484035200"; d="scan'208";a="230988581" Received: from elena-thinkpad-x230.fi.intel.com ([10.237.72.69]) by fmsmga004.fm.intel.com with ESMTP; 01 Mar 2017 02:42:30 -0800 From: Elena Reshetova To: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, peterz@infradead.org, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk, jlayton@poochiereds.net, bfields@fieldses.org, ebiederm@xmission.com, john.hammond@intel.com, Elena Reshetova , Hans Liljestrand , Kees Cook , David Windsor Subject: [PATCH 3/5] fs: convert mnt_namespace.count from atomic_t to refcount_t Date: Wed, 1 Mar 2017 12:42:15 +0200 Message-Id: <1488364937-12486-4-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1488364937-12486-1-git-send-email-elena.reshetova@intel.com> References: <1488364937-12486-1-git-send-email-elena.reshetova@intel.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@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/mount.h | 5 +++-- fs/namespace.c | 4 ++-- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/mount.h b/fs/mount.h index 2826543..106240d 100644 --- a/fs/mount.h +++ b/fs/mount.h @@ -3,9 +3,10 @@ #include #include #include +#include struct mnt_namespace { - atomic_t count; + refcount_t count; struct ns_common ns; struct mount * root; struct list_head list; @@ -110,7 +111,7 @@ static inline void detach_mounts(struct dentry *dentry) static inline void get_mnt_ns(struct mnt_namespace *ns) { - atomic_inc(&ns->count); + refcount_inc(&ns->count); } extern seqlock_t mount_lock; diff --git a/fs/namespace.c b/fs/namespace.c index 8bfad42..85cc8ca 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2888,7 +2888,7 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns) } new_ns->ns.ops = &mntns_operations; new_ns->seq = atomic64_add_return(1, &mnt_ns_seq); - atomic_set(&new_ns->count, 1); + refcount_set(&new_ns->count, 1); new_ns->root = NULL; INIT_LIST_HEAD(&new_ns->list); init_waitqueue_head(&new_ns->poll); @@ -3278,7 +3278,7 @@ void __init mnt_init(void) void put_mnt_ns(struct mnt_namespace *ns) { - if (!atomic_dec_and_test(&ns->count)) + if (!refcount_dec_and_test(&ns->count)) return; drop_collected_mounts(&ns->root->mnt); free_mnt_ns(ns);