🛡️ Sentinel: [MEDIUM] 서브프로세스 DoS 취약점 수정

.jules/sentinel.md

@@ -46,3 +46,7 @@
 **Vulnerability:** Argument Injection via relative paths starting with a hyphen in command-line utilities (CWE-88).
 **Learning:** Even when `ffmpeg` inputs are protected by `-i`, command-line utilities (like `ffprobe` and `ffmpeg` filters) can interpret user input (like a file path) starting with a hyphen (e.g., `-version.wav`) as options if passed as a relative path.
 **Prevention:** File paths must be converted to absolute paths using `.resolve()` before they are passed to `subprocess.run`. This prefixes the path with a root, drive, or UNC prefix rather than a leading hyphen, thereby averting the possibility of argument injection.
+## 2024-07-04 - 서브프로세스 타임아웃 부재로 인한 DoS 취약점
+**Vulnerability:** `subprocess.run` 호출 시 `timeout` 인자가 누락되어 외부 바이너리(ffmpeg, ffprobe 등)가 무한 대기 상태에 빠질 경우 시스템 리소스 고갈(DoS)이 발생할 수 있었습니다.
+**Learning:** Python의 `subprocess.run`은 기본적으로 타임아웃을 적용하지 않으므로, 신뢰할 수 없는 외부 명령이나 I/O 대기가 발생할 수 있는 경우 프로세스가 영구적으로 멈출 수 있습니다.
+**Prevention:** `subprocess.run`을 사용할 때는 항상 적절한 `timeout`(예: 프로브는 60초, 변환은 3600초)을 설정하고 `subprocess.TimeoutExpired` 예외를 처리하여 애플리케이션이 안전하게 복구될 수 있도록 해야 합니다.

media_shrinker.py

@@ -465,9 +465,13 @@ def probe_media(
         "-i",
         str(Path(source_path).resolve()),
     ]
-    completed = subprocess.run(
-        command, check=False, capture_output=True, text=True, shell=False
-    )
+    try:
+        completed = subprocess.run(
+            command, check=False, capture_output=True, text=True, shell=False, timeout=60
+        )
+    except subprocess.TimeoutExpired as exc:
+        raise MediaShrinkerError(f"ffprobe timed out for {source_path}") from exc
+
     if completed.returncode != 0:
         raise MediaShrinkerError(
             f"ffprobe failed for {source_path}: {completed.stderr.strip()}"
@@ -520,18 +524,23 @@ def detect_silence_intervals(
 ) -> list[SilenceInterval]:
     """Run ffmpeg silencedetect and return paired silence intervals."""
 
-    completed = subprocess.run(
-        build_silencedetect_command(
-            source_path,
-            ffmpeg_path=ffmpeg_path,
-            silence_noise=silence_noise,
-            silence_min_duration_seconds=silence_min_duration_seconds,
-        ),
-        check=False,
-        capture_output=True,
-        text=True,
-        shell=False,
-    )
+    try:
+        completed = subprocess.run(
+            build_silencedetect_command(
+                source_path,
+                ffmpeg_path=ffmpeg_path,
+                silence_noise=silence_noise,
+                silence_min_duration_seconds=silence_min_duration_seconds,
+            ),
+            check=False,
+            capture_output=True,
+            text=True,
+            shell=False,
+            timeout=3600,
+        )
+    except subprocess.TimeoutExpired as exc:
+        raise MediaShrinkerError(f"silencedetect timed out for {source_path}") from exc
+
     if completed.returncode != 0:
         raise MediaShrinkerError(
             f"silencedetect failed for {source_path}: {completed.stderr.strip()}"
@@ -646,13 +655,18 @@ def download_from_icloud(source_path: Path, *, brctl_path: str = "brctl") -> Non
         raise MediaShrinkerError(
             f"iCloud download requested but '{brctl_path}' was not found"
         )
-    completed = subprocess.run(
-        build_icloud_download_command(source_path, brctl_path=brctl_path),
-        check=False,
-        capture_output=True,
-        text=True,
-        shell=False,
-    )
+    try:
+        completed = subprocess.run(
+            build_icloud_download_command(source_path, brctl_path=brctl_path),
+            check=False,
+            capture_output=True,
+            text=True,
+            shell=False,
+            timeout=3600,
+        )
+    except subprocess.TimeoutExpired as exc:
+        raise MediaShrinkerError(f"iCloud download timed out for {source_path}") from exc
+
     if completed.returncode != 0:
         raise MediaShrinkerError(
             f"iCloud download failed for {source_path}: {completed.stderr.strip()}"
@@ -1590,10 +1604,12 @@ def _execute_plan(
         )
         try:
             completed = subprocess.run(
-                command, check=False, capture_output=True, text=True, shell=False
+                command, check=False, capture_output=True, text=True, shell=False, timeout=3600
             )
         except FileNotFoundError as exc:
             raise MediaShrinkerError(f"ffmpeg not found: {ffmpeg_path}") from exc
+        except subprocess.TimeoutExpired as exc:
+            raise MediaShrinkerError(f"ffmpeg timed out for {source}") from exc
 
         if completed.returncode != 0:
             raise MediaShrinkerError(
@@ -1658,13 +1674,17 @@ def _copy_macos_creation_time(
     creation_date = datetime.fromtimestamp(float(birthtime)).strftime(
         "%m/%d/%Y %H:%M:%S"
     )
-    subprocess.run(
-        [setfile_path, "-d", creation_date, str(dest.resolve())],
-        check=False,
-        capture_output=True,
-        text=True,
-        shell=False,
-    )
+    try:
+        subprocess.run(
+            [setfile_path, "-d", creation_date, str(dest.resolve())],
+            check=False,
+            capture_output=True,
+            text=True,
+            shell=False,
+            timeout=60,
+        )
+    except subprocess.TimeoutExpired:
+        pass
 
 
 def _format_result(root: Path, result: ConversionResult) -> str:

tests/test_media_shrinker.py

@@ -1705,7 +1705,6 @@ def test_attribute_copy_helpers_ignore_platform_errors(self) -> None:
 
 class FastPathTests(unittest.TestCase):
     def test_copy_extended_attributes_dummy(self) -> None:
-        import os
         from media_shrinker import _copy_extended_attributes
 
         # We need to hit lines 703-704
@@ -1720,7 +1719,6 @@ def test_copy_extended_attributes_dummy(self) -> None:
 
     def test_copy_macos_creation_time_dummy(self) -> None:
         from media_shrinker import _copy_macos_creation_time
-        import stat
 
         # Hit 1632
         class MockStat:
@@ -1747,7 +1745,6 @@ def test_format_result_dummy(self) -> None:
         self.assertIn("foo.txt", s)
 
     def test_copy_extended_attributes_dummy_success(self) -> None:
-        import os
         from media_shrinker import _copy_extended_attributes
 
         # Hit 703-704
@@ -1763,7 +1760,6 @@ def test_copy_extended_attributes_dummy_success(self) -> None:
 
     def test_copy_macos_creation_time_dummy_none(self) -> None:
         from media_shrinker import _copy_macos_creation_time
-        import stat
 
         # Hit 1632
         class MockStat:
@@ -1775,7 +1771,6 @@ class MockStat:
             _copy_macos_creation_time(MockStat(), dest, "/bin/echo")
 
     def test_copy_extended_attributes_dummy_set_fail(self) -> None:
-        import os
         from media_shrinker import _copy_extended_attributes
 
         # Hit 703-704
@@ -1792,7 +1787,6 @@ def test_copy_extended_attributes_dummy_set_fail(self) -> None:
 
     def test_copy_macos_creation_time_dummy_not_found(self) -> None:
         from media_shrinker import _copy_macos_creation_time
-        import stat
 
         # Hit 1632
         class MockStat:
@@ -1807,7 +1801,6 @@ class MockStat:
 
     def test_copy_macos_creation_time_dummy_success(self) -> None:
         from media_shrinker import _copy_macos_creation_time
-        import stat
 
         # Hit 1632
         class MockStat:
@@ -1838,7 +1831,6 @@ class MockStat:
                     preserve_file_attributes(src, dest)
 
     def test_copy_extended_attributes_dummy_success_branch(self) -> None:
-        import os
         from media_shrinker import _copy_extended_attributes
 
         # Hit 703-704
@@ -1856,7 +1848,6 @@ def test_copy_extended_attributes_dummy_success_branch(self) -> None:
 
     def test_copy_extended_attributes_dummy_listxattr_missing(self) -> None:
         import builtins
-        import os
         from media_shrinker import _copy_extended_attributes
 
         # Hit early return inside _copy_extended_attributes when OS doesn't support it
@@ -1877,7 +1868,6 @@ def fake_hasattr(obj, name):
 
     def test_preserve_file_attributes_chmod_error(self) -> None:
         from media_shrinker import preserve_file_attributes
-        import stat
 
         # Hit 703-704
         class MockStat:
@@ -1897,7 +1887,6 @@ class MockStat:
 
     def test_preserve_file_attributes_with_setfile(self) -> None:
         from media_shrinker import preserve_file_attributes
-        import stat
 
         # Hit 703-704
         class MockStat: