Limit SAMPLESPERPIXEL to avoid runtime DOS

Tests/test_file_tiff.py

@@ -4,7 +4,7 @@
 
 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 @@ def test_timeout(self):
             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 pytest.warns(UserWarning):
+                with Image.open(test_file):
+                    pass
+
 
 @pytest.mark.skipif(not is_win32(), reason="Windows only")
 class TestFileTiffW32:

docs/releasenotes/9.3.0.rst

@@ -49,6 +49,15 @@ decode the data in its natural CMYK mode, then convert it to RGB and rearrange
 the channels afterwards. Trying to load the data in an incorrect mode could
 result in a segmentation fault. This issue was introduced in Pillow 9.1.0.
 
+Limit SAMPLESPERPIXEL to avoid runtime DOS
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+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.
+This was introduced in Pillow 9.2.0, found with `OSS-Fuzz`_ and fixed by limiting
+``SAMPLESPERPIXEL`` to the number of planes that we can decode.
+
+
 Other Changes
 =============
 
@@ -88,3 +97,5 @@ Show all frames with ImageShow
 
 When calling :py:meth:`~PIL.Image.Image.show` or using
 :py:mod:`~PIL.ImageShow`, all frames will now be shown.
+
+.. _OSS-Fuzz: https://github.com/google/oss-fuzz

src/PIL/TiffImagePlugin.py

@@ -257,6 +257,8 @@
     (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 +1398,14 @@ def _setup(self):
             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.