From 19d31c5b036a46365584d7d97e87f7fe16150623 Mon Sep 17 00:00:00 2001
From: Lars Knoll <lars.knoll@digia.com>
Date: Thu, 24 Apr 2014 15:33:27 +0200
Subject: [PATCH] Don't crash on broken GIF images

Broken GIF images could set invalid width and height
values inside the image, leading to Qt creating a null
QImage for it. In that case we need to abort decoding
the image and return an error.

Initial patch by Rich Moore.

Backport of Id82a4036f478bd6e49c402d6598f57e7e5bb5e1e from Qt 5

Task-number: QTBUG-38367
Change-Id: I0680740018aaa8356d267b7af3f01fac3697312a
Security-advisory: CVE-2014-0190
---
 src/gui/image/qgifhandler.cpp |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/src/gui/image/qgifhandler.cpp
+++ b/src/gui/image/qgifhandler.cpp
@@ -366,6 +366,13 @@ int QGIFFormat::decode(QImage *image, co
                     return -1;
                 }
 
+                // Check if the previous attempt to create the image failed. If it
+                // did then the image is broken and we should give up.
+                if (image->isNull()) {
+                    state = Error;
+                    return -1;
+                }
+
                 disposePrevious(image);
                 disposed = false;