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 5/5] mm: convert mm_struct.mm_count from atomic_t to refcount_t
Date: Tue, 21 Feb 2017 11:58:44 +0200 [thread overview]
Message-ID: <1487671124-11188-6-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>
---
arch/blackfin/mach-common/smp.c | 2 +-
arch/x86/kernel/tboot.c | 2 +-
drivers/firmware/efi/arm-runtime.c | 2 +-
drivers/gpu/drm/amd/amdkfd/kfd_process.c | 2 +-
fs/userfaultfd.c | 3 +--
include/linux/mm_types.h | 2 +-
include/linux/sched.h | 6 +++---
kernel/fork.c | 2 +-
mm/debug.c | 2 +-
mm/init-mm.c | 2 +-
mm/mmu_notifier.c | 6 +++---
11 files changed, 15 insertions(+), 16 deletions(-)
diff --git a/arch/blackfin/mach-common/smp.c b/arch/blackfin/mach-common/smp.c
index bab73d2b..e08d250 100644
--- a/arch/blackfin/mach-common/smp.c
+++ b/arch/blackfin/mach-common/smp.c
@@ -423,7 +423,7 @@ void cpu_die(void)
(void)cpu_report_death();
refcount_dec(&init_mm.mm_users);
- atomic_dec(&init_mm.mm_count);
+ refcount_dec(&init_mm.mm_count);
local_irq_disable();
platform_cpu_die();
diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
index 39aaca5..fdbae72 100644
--- a/arch/x86/kernel/tboot.c
+++ b/arch/x86/kernel/tboot.c
@@ -103,7 +103,7 @@ static struct mm_struct tboot_mm = {
.mm_rb = RB_ROOT,
.pgd = swapper_pg_dir,
.mm_users = REFCOUNT_INIT(2),
- .mm_count = ATOMIC_INIT(1),
+ .mm_count = REFCOUNT_INIT(1),
.mmap_sem = __RWSEM_INITIALIZER(init_mm.mmap_sem),
.page_table_lock = __SPIN_LOCK_UNLOCKED(init_mm.page_table_lock),
.mmlist = LIST_HEAD_INIT(init_mm.mmlist),
diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
index 23e41f9..f0571f2 100644
--- a/drivers/firmware/efi/arm-runtime.c
+++ b/drivers/firmware/efi/arm-runtime.c
@@ -33,7 +33,7 @@ extern u64 efi_system_table;
static struct mm_struct efi_mm = {
.mm_rb = RB_ROOT,
.mm_users = REFCOUNT_INIT(2),
- .mm_count = ATOMIC_INIT(1),
+ .mm_count = REFCOUNT_INIT(1),
.mmap_sem = __RWSEM_INITIALIZER(efi_mm.mmap_sem),
.page_table_lock = __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
.mmlist = LIST_HEAD_INIT(efi_mm.mmlist),
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index ca5f2aa..d86ceec 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -204,7 +204,7 @@ static void kfd_process_destroy_delayed(struct rcu_head *rcu)
BUG_ON(!kfd_process_wq);
p = container_of(rcu, struct kfd_process, rcu);
- BUG_ON(atomic_read(&p->mm->mm_count) <= 0);
+ BUG_ON(refcount_read(&p->mm->mm_count) == 0);
mmdrop(p->mm);
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 3c421d0..1fd19ac 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -613,7 +613,7 @@ int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs)
ctx->features = octx->features;
ctx->released = false;
ctx->mm = vma->vm_mm;
- atomic_inc(&ctx->mm->mm_count);
+ mmgrab(ctx->mm);
userfaultfd_ctx_get(octx);
fctx->orig = octx;
@@ -1848,7 +1848,6 @@ static struct file *userfaultfd_file_create(int flags)
ctx->mm = current->mm;
/* prevent the mm struct to be freed */
mmgrab(ctx->mm);
-
file = anon_inode_getfile("[userfaultfd]", &userfaultfd_fops, ctx,
O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS));
if (IS_ERR(file)) {
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index af260d6..6445c58 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -427,7 +427,7 @@ struct mm_struct {
* Use mmgrab()/mmdrop() to modify. When this drops to 0, the
* &struct mm_struct is freed.
*/
- atomic_t mm_count;
+ refcount_t mm_count;
atomic_long_t nr_ptes; /* PTE page table pages */
#if CONFIG_PGTABLE_LEVELS > 2
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c21682c..41a2e52 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2924,14 +2924,14 @@ extern struct mm_struct * mm_alloc(void);
*/
static inline void mmgrab(struct mm_struct *mm)
{
- atomic_inc(&mm->mm_count);
+ refcount_inc(&mm->mm_count);
}
/* mmdrop drops the mm and the page tables */
extern void __mmdrop(struct mm_struct *);
static inline void mmdrop(struct mm_struct *mm)
{
- if (unlikely(atomic_dec_and_test(&mm->mm_count)))
+ if (unlikely(refcount_dec_and_test(&mm->mm_count)))
__mmdrop(mm);
}
@@ -2943,7 +2943,7 @@ static inline void mmdrop_async_fn(struct work_struct *work)
static inline void mmdrop_async(struct mm_struct *mm)
{
- if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
+ if (unlikely(refcount_dec_and_test(&mm->mm_count))) {
INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
schedule_work(&mm->async_put_work);
}
diff --git a/kernel/fork.c b/kernel/fork.c
index 60ff801..31c887c 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -760,7 +760,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
mm->mm_rb = RB_ROOT;
mm->vmacache_seqnum = 0;
refcount_set(&mm->mm_users, 1);
- atomic_set(&mm->mm_count, 1);
+ refcount_set(&mm->mm_count, 1);
init_rwsem(&mm->mmap_sem);
INIT_LIST_HEAD(&mm->mmlist);
mm->core_state = NULL;
diff --git a/mm/debug.c b/mm/debug.c
index 0866505..eebbd15 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -135,7 +135,7 @@ void dump_mm(const struct mm_struct *mm)
#endif
mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
mm->pgd, refcount_read(&mm->mm_users),
- atomic_read(&mm->mm_count),
+ refcount_read(&mm->mm_count),
atomic_long_read((atomic_long_t *)&mm->nr_ptes),
mm_nr_pmds((struct mm_struct *)mm),
mm->map_count,
diff --git a/mm/init-mm.c b/mm/init-mm.c
index 6927a72..8de5267 100644
--- a/mm/init-mm.c
+++ b/mm/init-mm.c
@@ -18,7 +18,7 @@ struct mm_struct init_mm = {
.mm_rb = RB_ROOT,
.pgd = swapper_pg_dir,
.mm_users = REFCOUNT_INIT(2),
- .mm_count = ATOMIC_INIT(1),
+ .mm_count = REFCOUNT_INIT(1),
.mmap_sem = __RWSEM_INITIALIZER(init_mm.mmap_sem),
.page_table_lock = __SPIN_LOCK_UNLOCKED(init_mm.page_table_lock),
.mmlist = LIST_HEAD_INIT(init_mm.mmlist),
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 7a2aa2d..c67f27e 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -348,7 +348,7 @@ void __mmu_notifier_mm_destroy(struct mm_struct *mm)
*/
void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm)
{
- BUG_ON(atomic_read(&mm->mm_count) <= 0);
+ BUG_ON(refcount_read(&mm->mm_count) == 0);
if (!hlist_unhashed(&mn->hlist)) {
/*
@@ -381,7 +381,7 @@ void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm)
*/
synchronize_srcu(&srcu);
- BUG_ON(atomic_read(&mm->mm_count) <= 0);
+ BUG_ON(refcount_read(&mm->mm_count) == 0);
mmdrop(mm);
}
@@ -401,7 +401,7 @@ void mmu_notifier_unregister_no_release(struct mmu_notifier *mn,
hlist_del_init_rcu(&mn->hlist);
spin_unlock(&mm->mmu_notifier_mm->lock);
- BUG_ON(atomic_read(&mm->mm_count) <= 0);
+ BUG_ON(refcount_read(&mm->mm_count) == 0);
mmdrop(mm);
}
EXPORT_SYMBOL_GPL(mmu_notifier_unregister_no_release);
--
2.7.4
--
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next prev parent reply other threads:[~2017-02-21 9:59 UTC|newest]
Thread overview: 11+ 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 ` [PATCH 2/5] mm: convert anon_vma.refcount " Elena Reshetova
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 ` Elena Reshetova [this message]
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 5/5] mm: convert mm_struct.mm_count 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 5/5] mm: convert mm_struct.mm_count from atomic_t to refcount_t Elena Reshetova
2017-02-20 13:16 ` kbuild test robot
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