[Scummvm-cvs-logs] SF.net SVN: scummvm:[55492] scummvm/trunk/engines/parallaction/graphics.cpp

[tdhs at users.sourceforge.net]

Revision: 55492
          http://scummvm.svn.sourceforge.net/scummvm/?rev=55492&view=rev
Author:   tdhs
Date:     2011-01-24 01:58:43 +0000 (Mon, 24 Jan 2011)

Log Message:
-----------
PARALLACTION: Improve safety of PathBuffer::getValue().

This will now avoid invalid memory reads and instead emit warnings if it is called with values outside of the expected data buffer or on a NULL buffer.

Modified Paths:
--------------
    scummvm/trunk/engines/parallaction/graphics.cpp

Modified: scummvm/trunk/engines/parallaction/graphics.cpp
===================================================================
--- scummvm/trunk/engines/parallaction/graphics.cpp	2011-01-24 01:36:11 UTC (rev 55491)
+++ scummvm/trunk/engines/parallaction/graphics.cpp	2011-01-24 01:58:43 UTC (rev 55492)
@@ -1110,7 +1110,15 @@
 }
 
 byte PathBuffer::getValue(uint16 x, uint16 y) const {
-	byte m = data[(x >> 3) + y * internalWidth];
+	byte m = 0;
+	if (data) {
+		uint index = (x >> 3) + y * internalWidth;
+		if (index < size)
+			m = data[index];
+		else
+			warning("PathBuffer::getValue(x: %d, y: %d) outside of data buffer of size %d", x, y, size);
+	} else
+		warning("PathBuffer::getValue() attempted to use NULL data buffer");
 	uint bit = bigEndian ? (x & 7) : (7 - (x & 7));
 	return ((1 << bit) & m) >> bit;
 }


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