From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752528AbdJTHts (ORCPT ); Fri, 20 Oct 2017 03:49:48 -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 S1752114AbdJTHsm (ORCPT ); Fri, 20 Oct 2017 03:48:42 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,405,1503385200"; d="scan'208";a="1207960123" 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 2/3] [S390] net: convert lcs_reply.refcnt from atomic_t to refcount_t Date: Fri, 20 Oct 2017 10:47:49 +0300 Message-Id: <1508485670-24070-3-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 lcs_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/lcs.c | 10 +++++----- drivers/s390/net/lcs.h | 3 ++- 2 files changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/s390/net/lcs.c b/drivers/s390/net/lcs.c index d01b5c2..d7344be 100644 --- a/drivers/s390/net/lcs.c +++ b/drivers/s390/net/lcs.c @@ -769,15 +769,15 @@ lcs_get_lancmd(struct lcs_card *card, int count) static void lcs_get_reply(struct lcs_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 lcs_put_reply(struct lcs_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); } @@ -793,7 +793,7 @@ lcs_alloc_reply(struct lcs_cmd *cmd) reply = kzalloc(sizeof(struct lcs_reply), GFP_ATOMIC); if (!reply) return NULL; - atomic_set(&reply->refcnt,1); + refcount_set(&reply->refcnt,1); reply->sequence_no = cmd->sequence_no; reply->received = 0; reply->rc = 0; diff --git a/drivers/s390/net/lcs.h b/drivers/s390/net/lcs.h index 150fcb4..3802f4f 100644 --- a/drivers/s390/net/lcs.h +++ b/drivers/s390/net/lcs.h @@ -4,6 +4,7 @@ #include #include #include +#include #include #define LCS_DBF_TEXT(level, name, text) \ @@ -270,7 +271,7 @@ struct lcs_buffer { struct lcs_reply { struct list_head list; __u16 sequence_no; - atomic_t refcnt; + refcount_t refcnt; /* Callback for completion notification. */ void (*callback)(struct lcs_card *, struct lcs_cmd *); wait_queue_head_t wait_q; -- 2.7.4