Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754365AbdCFOaA (ORCPT ); Mon, 6 Mar 2017 09:30:00 -0500 Received: from mga09.intel.com ([134.134.136.24]:43813 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753805AbdCFOZD (ORCPT ); Mon, 6 Mar 2017 09:25:03 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.35,254,1484035200"; d="scan'208";a="72745894" 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 05/29] drivers, md, bcache: convert cached_dev.count from atomic_t to refcount_t Date: Mon, 6 Mar 2017 16:20:52 +0200 Message-Id: <1488810076-3754-6-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 Content-Length: 3182 Lines: 99 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/bcache/bcache.h | 7 ++++--- drivers/md/bcache/super.c | 6 +++--- drivers/md/bcache/writeback.h | 2 +- 3 files changed, 8 insertions(+), 7 deletions(-) diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h index c3ea03c..de2be28 100644 --- a/drivers/md/bcache/bcache.h +++ b/drivers/md/bcache/bcache.h @@ -184,6 +184,7 @@ #include #include #include +#include #include #include @@ -299,7 +300,7 @@ struct cached_dev { struct semaphore sb_write_mutex; /* Refcount on the cache set. Always nonzero when we're caching. */ - atomic_t count; + refcount_t count; struct work_struct detach; /* @@ -805,13 +806,13 @@ do { \ static inline void cached_dev_put(struct cached_dev *dc) { - if (atomic_dec_and_test(&dc->count)) + if (refcount_dec_and_test(&dc->count)) schedule_work(&dc->detach); } static inline bool cached_dev_get(struct cached_dev *dc) { - if (!atomic_inc_not_zero(&dc->count)) + if (!refcount_inc_not_zero(&dc->count)) return false; /* Paired with the mb in cached_dev_attach */ diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index 85e3f21..cc36ce4 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -891,7 +891,7 @@ static void cached_dev_detach_finish(struct work_struct *w) closure_init_stack(&cl); BUG_ON(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)); - BUG_ON(atomic_read(&dc->count)); + BUG_ON(refcount_read(&dc->count)); mutex_lock(&bch_register_lock); @@ -1018,7 +1018,7 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c) * dc->c must be set before dc->count != 0 - paired with the mb in * cached_dev_get() */ - atomic_set(&dc->count, 1); + refcount_set(&dc->count, 1); /* Block writeback thread, but spawn it */ down_write(&dc->writeback_lock); @@ -1030,7 +1030,7 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c) if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) { bch_sectors_dirty_init(dc); atomic_set(&dc->has_dirty, 1); - atomic_inc(&dc->count); + refcount_inc(&dc->count); bch_writeback_queue(dc); } diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h index 629bd1a..5bac1b0 100644 --- a/drivers/md/bcache/writeback.h +++ b/drivers/md/bcache/writeback.h @@ -70,7 +70,7 @@ static inline void bch_writeback_add(struct cached_dev *dc) { if (!atomic_read(&dc->has_dirty) && !atomic_xchg(&dc->has_dirty, 1)) { - atomic_inc(&dc->count); + refcount_inc(&dc->count); if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) { SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY); -- 2.7.4