From e3736c3eb3a6f7c0966923b629c9f92b558aa9c7 Mon Sep 17 00:00:00 2001 From: Elena Reshetova Date: Mon, 20 Feb 2017 13:06:21 +0200 Subject: kvm: convert kvm.users_count from atomic_t to refcount_t MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Radim Krčmář --- virt/kvm/kvm_main.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'virt') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index cc4d6e0dd2a2..c6b7aff634be 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -617,7 +617,7 @@ static struct kvm *kvm_create_vm(unsigned long type) mutex_init(&kvm->lock); mutex_init(&kvm->irq_lock); mutex_init(&kvm->slots_lock); - atomic_set(&kvm->users_count, 1); + refcount_set(&kvm->users_count, 1); INIT_LIST_HEAD(&kvm->devices); r = kvm_arch_init_vm(kvm, type); @@ -747,13 +747,13 @@ static void kvm_destroy_vm(struct kvm *kvm) void kvm_get_kvm(struct kvm *kvm) { - atomic_inc(&kvm->users_count); + refcount_inc(&kvm->users_count); } EXPORT_SYMBOL_GPL(kvm_get_kvm); void kvm_put_kvm(struct kvm *kvm) { - if (atomic_dec_and_test(&kvm->users_count)) + if (refcount_dec_and_test(&kvm->users_count)) kvm_destroy_vm(kvm); } EXPORT_SYMBOL_GPL(kvm_put_kvm); @@ -3639,7 +3639,7 @@ static int kvm_debugfs_open(struct inode *inode, struct file *file, * To avoid the race between open and the removal of the debugfs * directory we test against the users count. */ - if (!atomic_add_unless(&stat_data->kvm->users_count, 1, 0)) + if (!refcount_inc_not_zero(&stat_data->kvm->users_count)) return -ENOENT; if (simple_attr_open(inode, file, get, set, fmt)) { -- cgit