diff options
| author | Elena Reshetova | 2017-02-20 13:06:21 +0200 |
|---|---|---|
| committer | Radim Krčmář | 2017-03-01 17:03:21 +0100 |
| commit | e3736c3eb3a6f7c0966923b629c9f92b558aa9c7 (patch) | |
| tree | 850c343552afe4d498411ba1e767aff4b43f0163 | |
| parent | bba82fd75694832b59433bf4e9d7ede8de1dfd42 (diff) | |
kvm: convert kvm.users_count from atomic_t to refcount_t
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>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
| -rw-r--r-- | include/linux/kvm_host.h | 3 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 8 |
2 files changed, 6 insertions, 5 deletions
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 8d69d5150748..2c14ad9809da 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -26,6 +26,7 @@ #include <linux/context_tracking.h> #include <linux/irqbypass.h> #include <linux/swait.h> +#include <linux/refcount.h> #include <asm/signal.h> #include <linux/kvm.h> @@ -401,7 +402,7 @@ struct kvm { #endif struct kvm_vm_stat stat; struct kvm_arch arch; - atomic_t users_count; + refcount_t users_count; #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET struct kvm_coalesced_mmio_ring *coalesced_mmio_ring; spinlock_t ring_lock; 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)) { |