Merge pull request #1669 from volatilityfoundation/fix_node_access

Prevent backtraces when the node head is smeared

volatility3/framework/symbols/linux/__init__.py

@@ -669,7 +669,7 @@ class IDStorage(ABC):
         raise NotImplementedError
 
     @abstractmethod
-    def get_head_node(self, tree) -> int:
+    def get_head_node(self, tree) -> Optional[int]:
         """Returns a pointer to the tree's head"""
         raise NotImplementedError
 
@@ -767,8 +767,11 @@ class XArray(IDStorage):
         node = self.nodep_to_node(nodep)
         return (node.shift // self.CHUNK_SHIFT) + 1
 
-    def get_head_node(self, tree) -> int:
-        return tree.xa_head
+    def get_head_node(self, tree) -> Optional[int]:
+        try:
+            return tree.xa_head
+        except exceptions.InvalidAddressException:
+            return None
 
     def node_is_internal(self, nodep) -> bool:
         return (nodep & self.XARRAY_TAG_MASK) == self.XARRAY_TAG_INTERNAL
@@ -876,8 +879,11 @@ class RadixTree(IDStorage):
 
         return height
 
-    def get_head_node(self, tree) -> int:
-        return tree.rnode
+    def get_head_node(self, tree) -> Optional[int]:
+        try:
+            return tree.rnode
+        except exceptions.InvalidAddressException:
+            return None
 
     def node_is_internal(self, nodep) -> bool:
         return (nodep & self.RADIX_TREE_INTERNAL_NODE) != 0