merge for issue #20778

1 files changed, 7 insertions, 5 deletions

diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index b19941e..cc5b8cc 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -1,6 +1,7 @@
 """Find modules used by a script, using introspection."""
 
 import dis
+import importlib._bootstrap
 import importlib.machinery
 import marshal
 import os
@@ -287,11 +288,12 @@ class ModuleFinder:
         if type == imp.PY_SOURCE:
             co = compile(fp.read()+'\n', pathname, 'exec')
         elif type == imp.PY_COMPILED:
-            if fp.read(4) != imp.get_magic():
-                self.msgout(2, "raise ImportError: Bad magic number", pathname)
-                raise ImportError("Bad magic number in %s" % pathname)
-            fp.read(4)
-            co = marshal.load(fp)
+            try:
+                marshal_data = importlib._bootstrap._validate_bytecode_header(fp.read())
+            except ImportError as exc:
+                self.msgout(2, "raise ImportError: " + str(exc), pathname)
+                raise
+            co = marshal.loads(marshal_data)
         else:
             co = None
         m = self.add_module(fqname)