CVE-2007-4559 Patch

src/elm_doc/tasks/assets.py

@@ -97,7 +97,29 @@
 class actions(Namespace):
     def extract_assets(run_config: Build):
         with tarfile.open(str(tarball)) as f:
-            f.extractall(str(run_config.output_path))
+
+            import os
+
+            def is_within_directory(directory, target):
+
+                abs_directory = os.path.abspath(directory)
+                abs_target = os.path.abspath(target)
+
+                prefix = os.path.commonprefix([abs_directory, abs_target])
+
+                return prefix == abs_directory
+
+            def safe_extract(tar, path=".", members=None, *, numeric_owner=False):
+
+                for member in tar.getmembers():
+                    member_path = os.path.join(path, member.name)
+                    if not is_within_directory(path, member_path):
+                        raise Exception("Attempted Path Traversal in Tar File")
+
+                tar.extractall(path, members, numeric_owner=numeric_owner) 
+
+
+            safe_extract(f, str(run_config.output_path))
         # decompress .gz files
         for asset in bundled_assets:
             if Path(asset).suffix == '.gz':

tests/conftest.py

@@ -132,7 +132,26 @@ def for_version(elm_version, root_dir, sources={}, package_overrides={}, copy_el
 def _extract_tarball(tarball, dest):
     with dest.as_cwd():
         with tarfile.open(str(tarball)) as tar:
-            tar.extractall()
+            def is_within_directory(directory, target):
+
+                abs_directory = os.path.abspath(directory)
+                abs_target = os.path.abspath(target)
+
+                prefix = os.path.commonprefix([abs_directory, abs_target])
+
+                return prefix == abs_directory
+
+            def safe_extract(tar, path=".", members=None, *, numeric_owner=False):
+
+                for member in tar.getmembers():
+                    member_path = os.path.join(path, member.name)
+                    if not is_within_directory(path, member_path):
+                        raise Exception("Attempted Path Traversal in Tar File")
+
+                tar.extractall(path, members, numeric_owner=numeric_owner) 
+
+
+            safe_extract(tar)
 
 
 # How to add a new entry: run `elm init` or its equivalent and