From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id 96C506B02F4 for ; Tue, 27 Jun 2017 07:49:01 -0400 (EDT) Received: by mail-pf0-f197.google.com with SMTP id h81so23987985pfh.15 for ; Tue, 27 Jun 2017 04:49:01 -0700 (PDT) Received: from mga02.intel.com (mga02.intel.com. [134.134.136.20]) by mx.google.com with ESMTPS id u72si1788824pfk.160.2017.06.27.04.49.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Jun 2017 04:49:00 -0700 (PDT) From: Elena Reshetova Subject: [PATCH 2/5] mm: convert anon_vma.refcount from atomic_t to refcount_t Date: Tue, 27 Jun 2017 14:48:44 +0300 Message-Id: <1498564127-11097-3-git-send-email-elena.reshetova@intel.com> 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: owner-linux-mm@kvack.org List-ID: 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 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 f683801..55d7f9e 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -79,7 +79,7 @@ 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; /* @@ -94,7 +94,7 @@ 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 @@ -423,7 +423,7 @@ 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; } @@ -472,7 +472,7 @@ 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; } @@ -531,7 +531,7 @@ 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; } @@ -546,7 +546,7 @@ 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 @@ -1585,7 +1585,7 @@ 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org