Take TIFF geometry tags from the image when saving

Tests/test_file_libtiff.py

@@ -399,21 +399,23 @@ def test_non_bytes(
         "tiffinfo",
         (
             {TiffImagePlugin.IMAGEWIDTH: 1 << 27},
+            {TiffImagePlugin.IMAGELENGTH: 1 << 27},
             {TiffImagePlugin.SAMPLESPERPIXEL: 3},
+            {TiffImagePlugin.PLANAR_CONFIGURATION: 2},
         ),
     )
     def test_geometry_tags(
         self, tiffinfo: dict[int, int], monkeypatch: pytest.MonkeyPatch, tmp_path: Path
     ) -> None:
-        # libtiff reads a scanline of the size described by the IMAGEWIDTH,
-        # SAMPLESPERPIXEL and BITSPERSAMPLE tags from a buffer that only holds one
-        # row of the image, so a tag describing a larger row must be rejected.
+        # The geometry of the image is used, not the geometry from tiffinfo.
+        # Otherwise libtiff would read past the end of the row buffer.
         monkeypatch.setattr(TiffImagePlugin, "WRITE_LIBTIFF", True)
 
         out = tmp_path / "temp.tif"
         im = hopper("L")
-        with pytest.raises(OSError, match="encoder error -8"):
-            im.save(out, tiffinfo=tiffinfo)
+        im.save(out, tiffinfo=tiffinfo)
+
+        assert_image_equal_tofile(im, out)
 
     @pytest.mark.parametrize(
         "tag, value",

docs/releasenotes/13.1.0.rst

@@ -59,6 +59,15 @@ use, now copy an image before writing to it if its memory is read-only, as
 memory-mapped image files, or modify the buffer behind an image created by
 :py:func:`~PIL.Image.frombuffer` or :py:func:`~PIL.Image.fromarrow`.
 
+Saving TIFF images with libtiff geometry tags
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When saving a TIFF image with libtiff, the ImageWidth, ImageLength,
+SamplesPerPixel and PlanarConfiguration tags are now always taken from the
+image, rather than from ``tiffinfo``, ``exif`` or the IFD of the original file.
+Previously, values that described a larger row than the image raised an
+:py:exc:`OSError`, and other values could produce an invalid file.
+
 Resizing I;16B and I;16N images
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

src/PIL/TiffImagePlugin.py

@@ -1825,9 +1825,6 @@ def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
 
     libtiff = WRITE_LIBTIFF or compression != "raw"
 
-    # required for color libtiff images
-    ifd[PLANAR_CONFIGURATION] = 1
-
     ifd[IMAGEWIDTH] = im.size[0]
     ifd[IMAGELENGTH] = im.size[1]
 
@@ -1846,6 +1843,8 @@ def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
     if isinstance(info, ImageFileDirectory_v1):
         info = info.to_v2()
     for key in info:
+        if libtiff and key in {IMAGEWIDTH, IMAGELENGTH}:
+            continue
         if isinstance(info, Image.Exif) and key in TiffTags.TAGS_V2_GROUPS:
             ifd[key] = info.get_ifd(key)
         else:
@@ -1855,6 +1854,9 @@ def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
         except Exception:
             pass  # might not be an IFD. Might not have populated type
 
+    # required for color libtiff images
+    ifd[PLANAR_CONFIGURATION] = 1
+
     legacy_ifd = {}
     if hasattr(im, "tag"):
         legacy_ifd = im.tag.to_v2()
@@ -1926,8 +1928,7 @@ def _save(im: Image.Image, fp: IO[bytes], filename: str | bytes) -> None:
 
     if bits != (1,):
         ifd[BITSPERSAMPLE] = bits
-        if len(bits) != 1:
-            ifd[SAMPLESPERPIXEL] = len(bits)
+    ifd[SAMPLESPERPIXEL] = len(bits)
     if extra is not None:
         ifd[EXTRASAMPLES] = extra
     if format != 1: