Limit expected number of characters to nencoding

Tests/test_font_pcf.py

@@ -49,6 +49,14 @@ def test_sanity(request, tmp_path):
     save_font(request, tmp_path)
 
 
+def test_less_than_256_characters():
+    with open("Tests/fonts/10x20-ISO8859-1-fewer-characters.pcf", "rb") as test_file:
+        font = PcfFontFile.PcfFontFile(test_file)
+    assert isinstance(font, FontFile.FontFile)
+    # check the number of characters in the font
+    assert len([_f for _f in font.glyph if _f]) == 127
+
+
 def test_invalid_file():
     with open("Tests/images/flower.jpg", "rb") as fp:
         with pytest.raises(SyntaxError):

src/PIL/PcfFontFile.py

@@ -84,8 +84,7 @@ def __init__(self, fp, charset_encoding="iso8859-1"):
         #
         # create glyph structure
 
-        for ch in range(256):
-            ix = encoding[ch]
+        for ch, ix in enumerate(encoding):
             if ix is not None:
                 x, y, l, r, w, a, d, f = metrics[ix]
                 glyph = (w, 0), (l, d - y, x + l, d), (0, 0, x, y), bitmaps[ix]
@@ -219,22 +218,21 @@ def _load_bitmaps(self, metrics):
         return bitmaps
 
     def _load_encoding(self):
-
-        # map character code to bitmap index
-        encoding = [None] * 256
-
         fp, format, i16, i32 = self._getformat(PCF_BDF_ENCODINGS)
 
         first_col, last_col = i16(fp.read(2)), i16(fp.read(2))
         first_row, last_row = i16(fp.read(2)), i16(fp.read(2))
 
         i16(fp.read(2))  # default
 
-        nencoding = (last_col - first_col + 1) * (last_row - first_row + 1)
+        nencoding = min(256, (last_col - first_col + 1) * (last_row - first_row + 1))
+
+        # map character code to bitmap index
+        encoding = [None] * nencoding
 
         encoding_offsets = [i16(fp.read(2)) for _ in range(nencoding)]
 
-        for i in range(first_col, len(encoding)):
+        for i in range(first_col, nencoding):
             try:
                 encoding_offset = encoding_offsets[
                     ord(bytearray([i]).decode(self.charset_encoding))
@@ -244,7 +242,5 @@ def _load_encoding(self):
             except UnicodeDecodeError:
                 # character is not supported in selected encoding
                 pass
-            except IndexError:
-                break
 
         return encoding