Prevent DOS with large SAMPLESPERPIXEL in Tiff IFD

A large value in the SAMPLESPERPIXEL tag could lead to a memory and
runtime DOS in TiffImagePlugin.py when setting up the context for
image decoding.

Tests/test_file_tiff.py

@@ -4,7 +4,7 @@ from io import BytesIO
 
 import pytest
 
-from PIL import Image, ImageFile, TiffImagePlugin
+from PIL import Image, ImageFile, TiffImagePlugin, UnidentifiedImageError
 from PIL.TiffImagePlugin import RESOLUTION_UNIT, X_RESOLUTION, Y_RESOLUTION
 
 from .helper import (
@@ -858,6 +858,19 @@ class TestFileTiff:
             im.load()
             ImageFile.LOAD_TRUNCATED_IMAGES = False
 
+    @pytest.mark.parametrize(
+        "test_file",
+        [
+            "Tests/images/oom-225817ca0f8c663be7ab4b9e717b02c661e66834.tif",
+        ],
+    )
+    @pytest.mark.timeout(2)
+    def test_oom(self, test_file):
+        with pytest.raises(UnidentifiedImageError):
+            with Image.open(test_file) as im:
+                im.load()
+
+
 
 @pytest.mark.skipif(not is_win32(), reason="Windows only")
 class TestFileTiffW32:

src/PIL/TiffImagePlugin.py

@@ -257,6 +257,8 @@ OPEN_INFO = {
     (MM, 8, (1,), 1, (8, 8, 8), ()): ("LAB", "LAB"),
 }
 
+MAX_SAMPLESPERPIXEL = max(len(key_tp[4]) for key_tp in OPEN_INFO.keys())
+
 PREFIXES = [
     b"MM\x00\x2A",  # Valid TIFF header with big-endian byte order
     b"II\x2A\x00",  # Valid TIFF header with little-endian byte order
@@ -1396,6 +1398,12 @@ class TiffImageFile(ImageFile.ImageFile):
             SAMPLESPERPIXEL,
             3 if self._compression == "tiff_jpeg" and photo in (2, 6) else 1,
         )
+
+        if samples_per_pixel > MAX_SAMPLESPERPIXEL:
+            # DOS check, samples_per_pixel can be a Long, and we extend the tuple below
+            logger.error("More samples per pixel than can be decoded: %s", samples_per_pixel)
+            raise SyntaxError("Invalid value for samples per pixel")
+
         if samples_per_pixel < bps_actual_count:
             # If a file has more values in bps_tuple than expected,
             # remove the excess.