From eaef29c3696cd021147e692360997f4c12377c60 Mon Sep 17 00:00:00 2001
From: Lumir Balhar <lbalhar@redhat.com>
Date: Mon, 14 Jun 2021 09:19:50 +0200
Subject: [PATCH 2/5] CVE-2021-28678

---
 src/PIL/BlpImagePlugin.py | 43 +++++++++++++++++++++------------------
 1 file changed, 23 insertions(+), 20 deletions(-)

diff --git a/src/PIL/BlpImagePlugin.py b/src/PIL/BlpImagePlugin.py
index d56d46c..846c83d 100644
--- a/src/PIL/BlpImagePlugin.py
+++ b/src/PIL/BlpImagePlugin.py
@@ -294,33 +294,36 @@ class _BLPBaseDecoder(ImageFile.PyDecoder):
             raise IOError("Truncated Blp file")
         return 0, 0
 
+    def _safe_read(self, length):
+        return ImageFile._safe_read(self.fd, length)
+
     def _read_palette(self):
         ret = []
         for i in range(256):
             try:
-                b, g, r, a = struct.unpack("<4B", self.fd.read(4))
+                b, g, r, a = struct.unpack("<4B", self._safe_read(4))
             except struct.error:
                 break
             ret.append((b, g, r, a))
         return ret
 
     def _read_blp_header(self):
-        self._blp_compression, = struct.unpack("<i", self.fd.read(4))
+        self._blp_compression, = struct.unpack("<i", self._safe_read(4))
 
-        self._blp_encoding, = struct.unpack("<b", self.fd.read(1))
-        self._blp_alpha_depth, = struct.unpack("<b", self.fd.read(1))
-        self._blp_alpha_encoding, = struct.unpack("<b", self.fd.read(1))
-        self._blp_mips, = struct.unpack("<b", self.fd.read(1))
+        self._blp_encoding, = struct.unpack("<b", self._safe_read(1))
+        self._blp_alpha_depth, = struct.unpack("<b", self._safe_read(1))
+        self._blp_alpha_encoding, = struct.unpack("<b", self._safe_read(1))
+        self._blp_mips, = struct.unpack("<b", self._safe_read(1))
 
-        self.size = struct.unpack("<II", self.fd.read(8))
+        self.size = struct.unpack("<II", self._safe_read(8))
 
         if self.magic == b"BLP1":
             # Only present for BLP1
-            self._blp_encoding, = struct.unpack("<i", self.fd.read(4))
-            self._blp_subtype, = struct.unpack("<i", self.fd.read(4))
+            self._blp_encoding, = struct.unpack("<i", self._safe_read(4))
+            self._blp_subtype, = struct.unpack("<i", self._safe_read(4))
 
-        self._blp_offsets = struct.unpack("<16I", self.fd.read(16 * 4))
-        self._blp_lengths = struct.unpack("<16I", self.fd.read(16 * 4))
+        self._blp_offsets = struct.unpack("<16I", self._safe_read(16 * 4))
+        self._blp_lengths = struct.unpack("<16I", self._safe_read(16 * 4))
 
 
 class BLP1Decoder(_BLPBaseDecoder):
@@ -333,7 +336,7 @@ class BLP1Decoder(_BLPBaseDecoder):
             if self._blp_encoding in (4, 5):
                 data = bytearray()
                 palette = self._read_palette()
-                _data = BytesIO(self.fd.read(self._blp_lengths[0]))
+                _data = BytesIO(self._safe_read(self._blp_lengths[0]))
                 while True:
                     try:
                         offset, = struct.unpack("<B", _data.read(1))
@@ -355,10 +358,10 @@ class BLP1Decoder(_BLPBaseDecoder):
     def _decode_jpeg_stream(self):
         from PIL.JpegImagePlugin import JpegImageFile
 
-        jpeg_header_size, = struct.unpack("<I", self.fd.read(4))
-        jpeg_header = self.fd.read(jpeg_header_size)
-        self.fd.read(self._blp_offsets[0] - self.fd.tell())  # What IS this?
-        data = self.fd.read(self._blp_lengths[0])
+        jpeg_header_size, = struct.unpack("<I", self._safe_read(4))
+        jpeg_header = self._safe_read(jpeg_header_size)
+        self._safe_read(self._blp_offsets[0] - self.fd.tell())  # What IS this?
+        data = self._safe_read(self._blp_lengths[0])
         data = jpeg_header + data
         data = BytesIO(data)
         image = JpegImageFile(data)
@@ -380,7 +383,7 @@ class BLP2Decoder(_BLPBaseDecoder):
             # Uncompressed or DirectX compression
 
             if self._blp_encoding == BLP_ENCODING_UNCOMPRESSED:
-                _data = BytesIO(self.fd.read(self._blp_lengths[0]))
+                _data = BytesIO(self._safe_read(self._blp_lengths[0]))
                 while True:
                     try:
                         offset, = struct.unpack("<B", _data.read(1))
@@ -394,7 +397,7 @@ class BLP2Decoder(_BLPBaseDecoder):
                     linesize = (self.size[0] + 3) // 4 * 8
                     for yb in range((self.size[1] + 3) // 4):
                         for d in decode_dxt1(
-                            self.fd.read(linesize),
+                            self._safe_read(linesize),
                             alpha=bool(self._blp_alpha_depth)
                         ):
                             data += d
@@ -402,13 +405,13 @@ class BLP2Decoder(_BLPBaseDecoder):
                 elif self._blp_alpha_encoding == BLP_ALPHA_ENCODING_DXT3:
                     linesize = (self.size[0] + 3) // 4 * 16
                     for yb in range((self.size[1] + 3) // 4):
-                        for d in decode_dxt3(self.fd.read(linesize)):
+                        for d in decode_dxt3(self._safe_read(linesize)):
                             data += d
 
                 elif self._blp_alpha_encoding == BLP_ALPHA_ENCODING_DXT5:
                     linesize = (self.size[0] + 3) // 4 * 16
                     for yb in range((self.size[1] + 3) // 4):
-                        for d in decode_dxt5(self.fd.read(linesize)):
+                        for d in decode_dxt5(self._safe_read(linesize)):
                             data += d
                 else:
                     raise BLPFormatError("Unsupported alpha encoding %r" % (
-- 
2.31.1