[flutter_tools] add validation of paths of contained files to os_utils _unpackArchive() (#96565)

packages/flutter_tools/lib/src/base/os.dart

@@ -539,10 +539,32 @@ class _WindowsUtils extends OperatingSystemUtils {
         continue;
       }
 
-      final File destFile = _fileSystem.file(_fileSystem.path.join(
+      final File destFile = _fileSystem.file(
+        _fileSystem.path.canonicalize(
+          _fileSystem.path.join(
+            targetDirectory.path,
+            archiveFile.name,
+          ),
+        ),
+      );
+
+      // Validate that the destFile is within the targetDirectory we want to
+      // extract to.
+      //
+      // See https://snyk.io/research/zip-slip-vulnerability for more context.
+      final String destinationFileCanonicalPath = _fileSystem.path.canonicalize(
+        destFile.path,
+      );
+      final String targetDirectoryCanonicalPath = _fileSystem.path.canonicalize(
         targetDirectory.path,
-        archiveFile.name,
-      ));
+      );
+      if (!destinationFileCanonicalPath.startsWith(targetDirectoryCanonicalPath)) {
+        throw StateError(
+          'Tried to extract the file $destinationFileCanonicalPath outside of the '
+          'target directory $targetDirectoryCanonicalPath',
+        );
+      }
+
       if (!destFile.parent.existsSync()) {
         destFile.parent.createSync(recursive: true);
       }

packages/flutter_tools/test/general.shard/base/os_test.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:archive/archive.dart';
 import 'package:file/file.dart';
 import 'package:file/memory.dart';
 import 'package:file_testing/file_testing.dart';
@@ -496,6 +497,33 @@ void main() {
       );
       expect(utils.name, 'Pretty Name');
     });
+
+    // See https://snyk.io/research/zip-slip-vulnerability for more context
+    testWithoutContext('Windows validates paths when unzipping', () {
+      // on POSIX systems we use the `unzip` binary, which will fail to extract
+      // files with paths outside the target directory
+      final OperatingSystemUtils utils = createOSUtils(FakePlatform(operatingSystem: 'windows'));
+      final MemoryFileSystem fs = MemoryFileSystem.test();
+      final File fakeZipFile = fs.file('archive.zip');
+      final Directory targetDirectory = fs.directory('output')..createSync(recursive: true);
+      const String content = 'hello, world!';
+      final Archive archive = Archive()..addFile(
+        // This file would be extracted outside of the target extraction dir
+        ArchiveFile(r'..\..\..\Target File.txt', content.length, content.codeUnits),
+      );
+      final List<int> zipData = ZipEncoder().encode(archive)!;
+      fakeZipFile.writeAsBytesSync(zipData);
+      expect(
+        () => utils.unzip(fakeZipFile, targetDirectory),
+        throwsA(
+          isA<StateError>().having(
+            (StateError error) => error.message,
+            'correct error message',
+            contains('Tried to extract the file '),
+          ),
+        ),
+      );
+    });
   });
 
   testWithoutContext('If unzip fails, include stderr in exception text', () {