From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754224AbdCFOfJ (ORCPT ); Mon, 6 Mar 2017 09:35:09 -0500 Received: from mga07.intel.com ([134.134.136.100]:47968 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752947AbdCFOY4 (ORCPT ); Mon, 6 Mar 2017 09:24:56 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.35,254,1484035200"; d="scan'208";a="72746011" From: Elena Reshetova To: gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, netdev@vger.kernel.org, linux1394-devel@lists.sourceforge.net, linux-bcache@vger.kernel.org, linux-raid@vger.kernel.org, linux-media@vger.kernel.org, devel@linuxdriverproject.org, linux-pci@vger.kernel.org, linux-s390@vger.kernel.org, fcoe-devel@open-fcoe.org, linux-scsi@vger.kernel.org, open-iscsi@googlegroups.com, devel@driverdev.osuosl.org, target-devel@vger.kernel.org, linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, peterz@infradead.org, Elena Reshetova , Hans Liljestrand , Kees Cook , David Windsor Subject: [PATCH 09/29] drivers, md: convert table_device.count from atomic_t to refcount_t Date: Mon, 6 Mar 2017 16:20:56 +0200 Message-Id: <1488810076-3754-10-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1488810076-3754-1-git-send-email-elena.reshetova@intel.com> References: <1488810076-3754-1-git-send-email-elena.reshetova@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- drivers/md/dm.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 9f37d7f..cba91c3 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -21,6 +21,7 @@ #include #include #include +#include #define DM_MSG_PREFIX "core" @@ -96,7 +97,7 @@ struct dm_md_mempools { struct table_device { struct list_head list; - atomic_t count; + refcount_t count; struct dm_dev dm_dev; }; @@ -680,10 +681,11 @@ int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode, format_dev_t(td->dm_dev.name, dev); - atomic_set(&td->count, 0); + refcount_set(&td->count, 1); list_add(&td->list, &md->table_devices); + } else { + refcount_inc(&td->count); } - atomic_inc(&td->count); mutex_unlock(&md->table_devices_lock); *result = &td->dm_dev; @@ -696,7 +698,7 @@ void dm_put_table_device(struct mapped_device *md, struct dm_dev *d) struct table_device *td = container_of(d, struct table_device, dm_dev); mutex_lock(&md->table_devices_lock); - if (atomic_dec_and_test(&td->count)) { + if (refcount_dec_and_test(&td->count)) { close_table_device(td, md); list_del(&td->list); kfree(td); @@ -713,7 +715,7 @@ static void free_table_devices(struct list_head *devices) struct table_device *td = list_entry(tmp, struct table_device, list); DMWARN("dm_destroy: %s still exists with %d references", - td->dm_dev.name, atomic_read(&td->count)); + td->dm_dev.name, refcount_read(&td->count)); kfree(td); } } -- 2.7.4