If Photoshop blocks are truncated, do not raise struct.error

Tests/test_file_tiff.py

@@ -16,6 +16,7 @@ from PIL import (
     TiffImagePlugin,
     TiffTags,
     UnidentifiedImageError,
+    _binary,
 )
 from PIL.TiffImagePlugin import RESOLUTION_UNIT, X_RESOLUTION, Y_RESOLUTION
 
@@ -941,6 +942,15 @@ class TestFileTiff:
                 4001,
             ]
 
+    def test_truncated_photoshop_blocks(self) -> None:
+        with Image.open("Tests/images/hopper.tif") as im:
+            assert isinstance(im, TiffImagePlugin.TiffImageFile)
+            im.tag_v2[34377] = b"8BIM"
+            assert im.get_photoshop_blocks() == {}
+
+            im.tag_v2[34377] = b"8BIM" + _binary.o16be(0) + _binary.o8(2) + b" " * 5
+            assert im.get_photoshop_blocks() == {}
+
     def test_tiff_chunks(self, tmp_path: Path) -> None:
         tmpfile = tmp_path / "temp.tif"
 

src/PIL/TiffImagePlugin.py

@@ -1287,10 +1287,13 @@ class TiffImageFile(ImageFile.ImageFile):
         blocks = {}
         val = self.tag_v2.get(ExifTags.Base.ImageResources)
         if val:
-            while val.startswith(b"8BIM"):
+            while val.startswith(b"8BIM") and len(val) >= 12:
                 id = i16(val[4:6])
                 n = math.ceil((val[6] + 1) / 2) * 2
-                size = i32(val[6 + n : 10 + n])
+                try:
+                    size = i32(val[6 + n : 10 + n])
+                except struct.error:
+                    break
                 data = val[10 + n : 10 + n + size]
                 blocks[id] = {"data": data}