Prevent opening P TGA images without a palette

Tests/test_file_tga.py

@@ -7,7 +7,7 @@
 
 import pytest
 
-from PIL import Image
+from PIL import Image, UnidentifiedImageError
 
 from .helper import assert_image_equal, assert_image_equal_tofile, hopper
 
@@ -65,6 +65,11 @@ def roundtrip(original_im) -> None:
                     roundtrip(original_im)
 
 
+def test_palette_depth_8(tmp_path: Path) -> None:
+    with pytest.raises(UnidentifiedImageError):
+        Image.open("Tests/images/p_8.tga")
+
+
 def test_palette_depth_16(tmp_path: Path) -> None:
     with Image.open("Tests/images/p_16.tga") as im:
         assert_image_equal_tofile(im.convert("RGB"), "Tests/images/p_16.png")
@@ -133,6 +138,11 @@ def test_small_palette(tmp_path: Path) -> None:
         assert reloaded.getpalette() == colors
 
 
+def test_missing_palette() -> None:
+    with Image.open("Tests/images/dilation4.lut") as im:
+        assert im.mode == "L"
+
+
 def test_save_wrong_mode(tmp_path: Path) -> None:
     im = hopper("PA")
     out = str(tmp_path / "temp.tga")

src/PIL/TgaImagePlugin.py

@@ -85,7 +85,7 @@ def _open(self) -> None:
             elif depth == 16:
                 self._mode = "LA"
         elif imagetype in (1, 9):
-            self._mode = "P"
+            self._mode = "P" if colormaptype else "L"
         elif imagetype in (2, 10):
             self._mode = "RGB"
             if depth == 32:
@@ -128,6 +128,9 @@ def _open(self) -> None:
                 self.palette = ImagePalette.raw(
                     "BGRA", b"\0" * 4 * start + self.fp.read(4 * size)
                 )
+            else:
+                msg = "unknown TGA map depth"
+                raise SyntaxError(msg)
 
         # setup tile descriptor
         try: