[runtime] Fix a race in mono_class_get_virtual_methods () which happens when klass...

diff --git a/mono/metadata/class.c b/mono/metadata/class.c
index ee0695ceccfbdb32dd39229a366fef7f3f01824d..4ed4f39da3dc5d648fa30936fb8d50f1d3fd7974 100644 (file)
--- a/mono/metadata/class.c
+++ b/mono/metadata/class.c
@@ -9106,10 +9106,25 @@ mono_class_get_methods (MonoClass* klass, gpointer *iter)
 static MonoMethod*
 mono_class_get_virtual_methods (MonoClass* klass, gpointer *iter)
 {
-       MonoMethod** method;
+       gboolean static_iter = FALSE;
+
        if (!iter)
                return NULL;
-       if (klass->methods || !MONO_CLASS_HAS_STATIC_METADATA (klass)) {
+
+       /*
+        * If the lowest bit of the iterator is 1, this is an iterator for static metadata,
+        * and the upper bits contain an index. Otherwise, the iterator is a pointer into
+        * klass->methods.
+        */
+       if ((gsize)(*iter) & 1)
+               static_iter = TRUE;
+       /* Use the static metadata only if klass->methods is not yet initialized */
+       if (!static_iter && !(klass->methods || !MONO_CLASS_HAS_STATIC_METADATA (klass)))
+               static_iter = TRUE;
+
+       if (!static_iter) {
+               MonoMethod** methodptr;
+
                if (!*iter) {
                        mono_class_setup_methods (klass);
                        /*
@@ -9119,20 +9134,22 @@ mono_class_get_virtual_methods (MonoClass* klass, gpointer *iter)
                        if (!klass->methods)
                                return NULL;
                        /* start from the first */
-                       method = &klass->methods [0];
+                       methodptr = &klass->methods [0];
                } else {
-                       method = (MonoMethod **)*iter;
-                       method++;
+                       methodptr = (MonoMethod **)*iter;
+                       methodptr++;
                }
+               if (*iter)
+                       g_assert ((guint64)(*iter) > 0x100);
                int mcount = mono_class_get_method_count (klass);
-               while (method < &klass->methods [mcount]) {
-                       if (*method && ((*method)->flags & METHOD_ATTRIBUTE_VIRTUAL))
+               while (methodptr < &klass->methods [mcount]) {
+                       if (*methodptr && ((*methodptr)->flags & METHOD_ATTRIBUTE_VIRTUAL))
                                break;
-                       method ++;
+                       methodptr ++;
                }
-               if (method < &klass->methods [mcount]) {
-                       *iter = method;
-                       return *method;
+               if (methodptr < &klass->methods [mcount]) {
+                       *iter = methodptr;
+                       return *methodptr;
                } else {
                        return NULL;
                }
@@ -9144,7 +9161,7 @@ mono_class_get_virtual_methods (MonoClass* klass, gpointer *iter)
                if (!*iter) {
                        start_index = 0;
                } else {
-                       start_index = GPOINTER_TO_UINT (*iter);
+                       start_index = GPOINTER_TO_UINT (*iter) >> 1;
                }
 
                int first_idx = mono_class_get_first_method_idx (klass);
@@ -9165,7 +9182,7 @@ mono_class_get_virtual_methods (MonoClass* klass, gpointer *iter)
                        mono_error_cleanup (&error); /* FIXME don't swallow the error */
 
                        /* Add 1 here so the if (*iter) check fails */
-                       *iter = GUINT_TO_POINTER (i + 1);
+                       *iter  = GUINT_TO_POINTER (((i + 1) << 1) | 1);
                        return res;
                } else {
                        return NULL;