From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752303AbdJTHsw (ORCPT ); Fri, 20 Oct 2017 03:48:52 -0400 Received: from mga02.intel.com ([134.134.136.20]:54787 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752028AbdJTHss (ORCPT ); Fri, 20 Oct 2017 03:48:48 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,405,1503385200"; d="scan'208";a="1207960124" From: Elena Reshetova To: linux-s390@vger.kernel.org Cc: linux-kernel@vger.kernel.org, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, jwi@linux.vnet.ibm.com, ubraun@linux.vnet.ibm.com, peterz@infradead.org, keescook@chromium.org, Elena Reshetova Subject: [PATCH 3/3] [S390] qeth: convert qeth_reply.refcnt from atomic_t to refcount_t Date: Fri, 20 Oct 2017 10:47:50 +0300 Message-Id: <1508485670-24070-4-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1508485670-24070-1-git-send-email-elena.reshetova@intel.com> References: <1508485670-24070-1-git-send-email-elena.reshetova@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 qeth_reply.refcnt 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 --- drivers/s390/net/qeth_core.h | 3 ++- drivers/s390/net/qeth_core_main.c | 10 +++++----- 2 files changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h index 91fcadb..49ba742 100644 --- a/drivers/s390/net/qeth_core.h +++ b/drivers/s390/net/qeth_core.h @@ -20,6 +20,7 @@ #include #include #include +#include #include #include @@ -645,7 +646,7 @@ struct qeth_reply { int rc; void *param; struct qeth_card *card; - atomic_t refcnt; + refcount_t refcnt; }; struct qeth_card_blkt { diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c index 68e118f..86e4c5d 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -559,7 +559,7 @@ static struct qeth_reply *qeth_alloc_reply(struct qeth_card *card) reply = kzalloc(sizeof(struct qeth_reply), GFP_ATOMIC); if (reply) { - atomic_set(&reply->refcnt, 1); + refcount_set(&reply->refcnt, 1); atomic_set(&reply->received, 0); reply->card = card; } @@ -568,14 +568,14 @@ static struct qeth_reply *qeth_alloc_reply(struct qeth_card *card) static void qeth_get_reply(struct qeth_reply *reply) { - WARN_ON(atomic_read(&reply->refcnt) <= 0); - atomic_inc(&reply->refcnt); + WARN_ON(refcount_read(&reply->refcnt) == 0); + refcount_inc(&reply->refcnt); } static void qeth_put_reply(struct qeth_reply *reply) { - WARN_ON(atomic_read(&reply->refcnt) <= 0); - if (atomic_dec_and_test(&reply->refcnt)) + WARN_ON(refcount_read(&reply->refcnt) == 0); + if (refcount_dec_and_test(&reply->refcnt)) kfree(reply); } -- 2.7.4