bitbake: data_smart: Improve override recursion handling

When expanding OVERRIDES, its possible someone might try and override a variable
that is used in OVERRIDES. This could lead to infinite recursion. Add in
guards against this.

(Bitbake rev: 07d773369f571028c2cf82dd1f65d9731af6d00e)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/data_smart.py

@@ -313,6 +313,7 @@ class DataSmart(MutableMapping):
         self.overridedata = {}
         self.overrides = None
         self.overridevars = set(["OVERRIDES", "FILE"])
+        self.inoverride = False
 
     def enableTracking(self):
         self._tracking = True
@@ -363,8 +364,13 @@ class DataSmart(MutableMapping):
 
     def need_overrides(self):
         if self.overrides is None:
+            if self.inoverride:
+                return
+            self.inoverride = True
+            # Can end up here recursively so setup dummy values
             self.overrides = []
             self.overrides = (self.getVar("OVERRIDES", True) or "").split(":") or []
+            self.inoverride = False
             self.expand_cache = {}
 
     def initVar(self, var):