File fix-a-division-by-zero.patch of Package libqt4

From: Richard J. Moore <rich@kde.org>
Date: Tue, 24 Feb 2015 19:02:35 +0000
Subject: Fix a division by zero when processing malformed BMP files.
X-Git-Url: http://quickgit.kde.org/?p=qt.git&a=commitdiff&h=e50aa2252cdd5cb53eef7d8c4503c7edff634f68
---
Fix a division by zero when processing malformed BMP files.

This fixes a division by 0 when processing a maliciously crafted BMP
file. No impact beyond DoS.

Backport of 661f6bfd032dacc62841037732816a583640e187

Task-number: QTBUG-44547
Change-Id: I43f06e752b11cb50669101460902a82b885ae618
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---


--- a/src/gui/image/qbmphandler.cpp
+++ b/src/gui/image/qbmphandler.cpp
@@ -319,10 +319,16 @@
         }
     } else if (comp == BMP_BITFIELDS && (nbits == 16 || nbits == 32)) {
         red_shift = calc_shift(red_mask);
+        if (((red_mask >> red_shift) + 1) == 0)
+            return false;
         red_scale = 256 / ((red_mask >> red_shift) + 1);
         green_shift = calc_shift(green_mask);
+        if (((green_mask >> green_shift) + 1) == 0)
+            return false;
         green_scale = 256 / ((green_mask >> green_shift) + 1);
         blue_shift = calc_shift(blue_mask);
+        if (((blue_mask >> blue_shift) + 1) == 0)
+            return false;
         blue_scale = 256 / ((blue_mask >> blue_shift) + 1);
     } else if (comp == BMP_RGB && (nbits == 24 || nbits == 32)) {
         blue_mask = 0x000000ff;
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