From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752978AbdF0LtR (ORCPT ); Tue, 27 Jun 2017 07:49:17 -0400 Received: from mga01.intel.com ([192.55.52.88]:7756 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752870AbdF0LtE (ORCPT ); Tue, 27 Jun 2017 07:49:04 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.39,399,1493708400"; d="scan'208";a="985677723" From: Elena Reshetova To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, peterz@infradead.org, gregkh@linuxfoundation.org, keescook@chromium.org, viro@zeniv.linux.org.uk, catalin.marinas@arm.com, mingo@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, luto@kernel.org, Elena Reshetova , Hans Liljestrand , David Windsor Subject: [PATCH 3/5] mm: convert kmemleak_object.use_count from atomic_t to refcount_t Date: Tue, 27 Jun 2017 14:48:45 +0300 Message-Id: <1498564127-11097-4-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1498564127-11097-1-git-send-email-elena.reshetova@intel.com> References: <1498564127-11097-1-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 --- mm/kmemleak.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 20036d4..8755a99 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -107,7 +107,7 @@ #include #include -#include +#include #include #include @@ -156,7 +156,7 @@ struct kmemleak_object { struct rb_node rb_node; struct rcu_head rcu; /* object_list lockless traversal */ /* object usage count; object freed when use_count == 0 */ - atomic_t use_count; + refcount_t use_count; unsigned long pointer; size_t size; /* minimum number of a pointers found before it is considered leak */ @@ -436,7 +436,7 @@ static struct kmemleak_object *lookup_object(unsigned long ptr, int alias) */ static int get_object(struct kmemleak_object *object) { - return atomic_inc_not_zero(&object->use_count); + return refcount_inc_not_zero(&object->use_count); } /* @@ -469,7 +469,7 @@ static void free_object_rcu(struct rcu_head *rcu) */ static void put_object(struct kmemleak_object *object) { - if (!atomic_dec_and_test(&object->use_count)) + if (!refcount_dec_and_test(&object->use_count)) return; /* should only get here after delete_object was called */ @@ -558,7 +558,7 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size, INIT_LIST_HEAD(&object->gray_list); INIT_HLIST_HEAD(&object->area_list); spin_lock_init(&object->lock); - atomic_set(&object->use_count, 1); + refcount_set(&object->use_count, 1); object->flags = OBJECT_ALLOCATED; object->pointer = ptr; object->size = size; @@ -631,7 +631,7 @@ static void __delete_object(struct kmemleak_object *object) unsigned long flags; WARN_ON(!(object->flags & OBJECT_ALLOCATED)); - WARN_ON(atomic_read(&object->use_count) < 1); + WARN_ON(refcount_read(&object->use_count) < 1); /* * Locking here also ensures that the corresponding memory block @@ -1398,9 +1398,9 @@ static void kmemleak_scan(void) * With a few exceptions there should be a maximum of * 1 reference to any object at this point. */ - if (atomic_read(&object->use_count) > 1) { + if (refcount_read(&object->use_count) > 1) { pr_debug("object->use_count = %d\n", - atomic_read(&object->use_count)); + refcount_read(&object->use_count)); dump_object_info(object); } #endif -- 2.7.4