From 7a0aea5806d57e0e7c5187fbc9c2937a16e0bca1 Mon Sep 17 00:00:00 2001
From: Eric Soroos <eric-github@soroos.net>
Date: Thu, 17 Dec 2020 00:17:53 +0100
Subject: [PATCH] Fix for CVE CVE-2020-35655 - Read Overflow in PCX Decoding.

* Don't trust the image to specify a buffer size
---
 src/PIL/PcxImagePlugin.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/PIL/PcxImagePlugin.py b/src/PIL/PcxImagePlugin.py
index 564713a..17bbd18 100644
--- a/src/PIL/PcxImagePlugin.py
+++ b/src/PIL/PcxImagePlugin.py
@@ -63,9 +63,9 @@ class PcxImageFile(ImageFile.ImageFile):
         version = i8(s[1])
         bits = i8(s[3])
         planes = i8(s[65])
-        stride = i16(s, 66)
+        ignored_stride = i16(s, 66)
         logger.debug("PCX version %s, bits %s, planes %s, stride %s",
-                     version, bits, planes, stride)
+                     version, bits, planes, ignored_stride)
 
         self.info["dpi"] = i16(s, 12), i16(s, 14)
 
@@ -102,6 +102,11 @@ class PcxImageFile(ImageFile.ImageFile):
         self.mode = mode
         self.size = bbox[2]-bbox[0], bbox[3]-bbox[1]
 
+        # don't trust the passed in stride. Calculate for ourselves.
+        # CVE-2020-35653
+        stride = (self.size[0] * bits + 7) // 8
+        stride += stride % 2
+
         bbox = (0, 0) + self.size
         logger.debug("size: %sx%s", *self.size)
 
-- 
2.29.2