From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752737AbdBTKtb (ORCPT ); Mon, 20 Feb 2017 05:49:31 -0500 Received: from mga04.intel.com ([192.55.52.120]:30658 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752634AbdBTKt3 (ORCPT ); Mon, 20 Feb 2017 05:49:29 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.35,186,1484035200"; d="scan'208";a="1132318368" From: Elena Reshetova To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, peterz@infradead.org, gregkh@linuxfoundation.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 , Kees Cook , David Windsor Subject: [PATCH 2/5] mm: convert anon_vma.refcount from atomic_t to refcount_t Date: Mon, 20 Feb 2017 12:49:11 +0200 Message-Id: <1487587754-10610-3-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1487587754-10610-1-git-send-email-elena.reshetova@intel.com> References: <1487587754-10610-1-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 --- include/linux/rmap.h | 7 ++++--- mm/rmap.c | 14 +++++++------- 2 files changed, 11 insertions(+), 10 deletions(-) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 8c89e90..a8f4a97 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -10,6 +10,7 @@ #include #include #include +#include /* * The anon_vma heads a list of private "related" vmas, to scan if @@ -35,7 +36,7 @@ struct anon_vma { * the reference is responsible for clearing up the * anon_vma if they are the last user on release */ - atomic_t refcount; + refcount_t refcount; /* * Count of child anon_vmas and VMAs which points to this anon_vma. @@ -102,14 +103,14 @@ enum ttu_flags { #ifdef CONFIG_MMU static inline void get_anon_vma(struct anon_vma *anon_vma) { - atomic_inc(&anon_vma->refcount); + refcount_inc(&anon_vma->refcount); } void __put_anon_vma(struct anon_vma *anon_vma); static inline void put_anon_vma(struct anon_vma *anon_vma) { - if (atomic_dec_and_test(&anon_vma->refcount)) + if (refcount_dec_and_test(&anon_vma->refcount)) __put_anon_vma(anon_vma); } diff --git a/mm/rmap.c b/mm/rmap.c index 8774791..3321c86 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -77,7 +77,7 @@ static inline struct anon_vma *anon_vma_alloc(void) anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); if (anon_vma) { - atomic_set(&anon_vma->refcount, 1); + refcount_set(&anon_vma->refcount, 1); anon_vma->degree = 1; /* Reference for first vma */ anon_vma->parent = anon_vma; /* @@ -92,7 +92,7 @@ static inline struct anon_vma *anon_vma_alloc(void) static inline void anon_vma_free(struct anon_vma *anon_vma) { - VM_BUG_ON(atomic_read(&anon_vma->refcount)); + VM_BUG_ON(refcount_read(&anon_vma->refcount)); /* * Synchronize against page_lock_anon_vma_read() such that @@ -421,7 +421,7 @@ static void anon_vma_ctor(void *data) struct anon_vma *anon_vma = data; init_rwsem(&anon_vma->rwsem); - atomic_set(&anon_vma->refcount, 0); + refcount_set(&anon_vma->refcount, 0); anon_vma->rb_root = RB_ROOT; } @@ -470,7 +470,7 @@ struct anon_vma *page_get_anon_vma(struct page *page) goto out; anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); - if (!atomic_inc_not_zero(&anon_vma->refcount)) { + if (!refcount_inc_not_zero(&anon_vma->refcount)) { anon_vma = NULL; goto out; } @@ -529,7 +529,7 @@ struct anon_vma *page_lock_anon_vma_read(struct page *page) } /* trylock failed, we got to sleep */ - if (!atomic_inc_not_zero(&anon_vma->refcount)) { + if (!refcount_inc_not_zero(&anon_vma->refcount)) { anon_vma = NULL; goto out; } @@ -544,7 +544,7 @@ struct anon_vma *page_lock_anon_vma_read(struct page *page) rcu_read_unlock(); anon_vma_lock_read(anon_vma); - if (atomic_dec_and_test(&anon_vma->refcount)) { + if (refcount_dec_and_test(&anon_vma->refcount)) { /* * Oops, we held the last refcount, release the lock * and bail -- can't simply use put_anon_vma() because @@ -1577,7 +1577,7 @@ void __put_anon_vma(struct anon_vma *anon_vma) struct anon_vma *root = anon_vma->root; anon_vma_free(anon_vma); - if (root != anon_vma && atomic_dec_and_test(&root->refcount)) + if (root != anon_vma && refcount_dec_and_test(&root->refcount)) anon_vma_free(root); } -- 2.7.4