Fix CVE-2016-10093:

http://bugzilla.maptools.org/show_bug.cgi?id=2610
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-10093
https://security-tracker.debian.org/tracker/CVE-2016-10093

2016-12-03 Even Rouault <even.rouault at spatialys.com>

        * tools/tiffcp.c: fix uint32 underflow/overflow that can cause
	heap-based buffer overflow.
        Reported by Agostino Sarubbo.
        Fixes http://bugzilla.maptools.org/show_bug.cgi?id=2610

/cvs/maptools/cvsroot/libtiff/ChangeLog,v  <--  ChangeLog
new revision: 1.1187; previous revision: 1.1186
/cvs/maptools/cvsroot/libtiff/tools/tiffcp.c,v  <--  tools/tiffcp.c
new revision: 1.59; previous revision: 1.58

Index: libtiff/tools/tiffcp.c
===================================================================
RCS file: /cvs/maptools/cvsroot/libtiff/tools/tiffcp.c,v
retrieving revision 1.58
retrieving revision 1.59
diff -u -r1.58 -r1.59
--- libtiff/tools/tiffcp.c	3 Dec 2016 15:44:15 -0000	1.58
+++ libtiff/tools/tiffcp.c	3 Dec 2016 16:40:01 -0000	1.59
@@ -1163,7 +1163,7 @@
 
 static void
 cpStripToTile(uint8* out, uint8* in,
-    uint32 rows, uint32 cols, int outskew, int inskew)
+    uint32 rows, uint32 cols, int outskew, int64 inskew)
 {
 	while (rows-- > 0) {
 		uint32 j = cols;
@@ -1320,7 +1320,7 @@
 	tdata_t tilebuf;
 	uint32 imagew = TIFFScanlineSize(in);
 	uint32 tilew  = TIFFTileRowSize(in);
-	int iskew = imagew - tilew;
+	int64 iskew = (int64)imagew - (int64)tilew;
 	uint8* bufp = (uint8*) buf;
 	uint32 tw, tl;
 	uint32 row;
@@ -1348,7 +1348,7 @@
 				status = 0;
 				goto done;
 			}
-			if (colb + tilew > imagew) {
+			if (colb > iskew) {
 				uint32 width = imagew - colb;
 				uint32 oskew = tilew - width;
 				cpStripToTile(bufp + colb,