From: Elena Reshetova <elena.reshetova@intel.com>
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 <elena.reshetova@intel.com>,
Hans Liljestrand <ishkamiel@gmail.com>,
Kees Cook <keescook@chromium.org>,
David Windsor <dwindsor@gmail.com>
Subject: [PATCH 2/5] mm: convert anon_vma.refcount from atomic_t to refcount_t
Date: Tue, 21 Feb 2017 11:58:41 +0200 [thread overview]
Message-ID: <1487671124-11188-3-git-send-email-elena.reshetova@intel.com> (raw)
In-Reply-To: <1487671124-11188-1-git-send-email-elena.reshetova@intel.com>
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 <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
---
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 <linux/rwsem.h>
#include <linux/memcontrol.h>
#include <linux/highmem.h>
+#include <linux/refcount.h>
/*
* 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
next prev parent reply other threads:[~2017-02-21 9:59 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-21 9:58 [PATCH 0/5] mm subsystem refcounter conversions Elena Reshetova
2017-02-21 9:58 ` [PATCH 1/5] mm: convert bdi_writeback_congested.refcnt from atomic_t to refcount_t Elena Reshetova
2017-02-21 9:58 ` Elena Reshetova [this message]
2017-02-21 9:58 ` [PATCH 3/5] mm: convert kmemleak_object.use_count " Elena Reshetova
2017-02-21 9:58 ` [PATCH 4/5] mm: convert mm_struct.mm_users " Elena Reshetova
2017-02-21 9:58 ` [PATCH 5/5] mm: convert mm_struct.mm_count " Elena Reshetova
2017-03-01 1:21 ` [PATCH 0/5] mm subsystem refcounter conversions Andrew Morton
2017-03-18 16:37 ` Herbert Xu
-- strict thread matches above, loose matches on Subject: below --
2017-06-27 11:48 [PATCH 0/5] v2 " Elena Reshetova
2017-06-27 11:48 ` [PATCH 2/5] mm: convert anon_vma.refcount from atomic_t to refcount_t Elena Reshetova
2017-02-20 10:49 [PATCH 0/5] mm subsystem refcounter conversions Elena Reshetova
2017-02-20 10:49 ` [PATCH 2/5] mm: convert anon_vma.refcount from atomic_t to refcount_t Elena Reshetova
2017-04-22 10:44 ` zhong jiang
2017-04-24 10:20 ` Reshetova, Elena
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