Fix NULL pointer dereference in TIFFReadRawData():

http://bugzilla.maptools.org/show_bug.cgi?id=2594


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

        * tools/tiffinfo.c: fix null pointer dereference in -r mode when
        * the
image has
        no StripByteCount tag.
        Reported by Agostino Sarubbo.
        Fixes http://bugzilla.maptools.org/show_bug.cgi?id=2594

/cvs/maptools/cvsroot/libtiff/ChangeLog,v  <--  ChangeLog
new revision: 1.1182; previous revision: 1.1181
/cvs/maptools/cvsroot/libtiff/tools/tiffinfo.c,v  <--  tools/tiffinfo.c
new revision: 1.26; previous revision: 1.25

Index: libtiff/tools/tiffinfo.c
===================================================================
RCS file: /cvs/maptools/cvsroot/libtiff/tools/tiffinfo.c,v
retrieving revision 1.25
retrieving revision 1.26
diff -u -r1.25 -r1.26
--- libtiff/tools/tiffinfo.c	12 Nov 2016 20:06:05 -0000	1.25
+++ libtiff/tools/tiffinfo.c	3 Dec 2016 14:18:49 -0000	1.26
@@ -1,4 +1,4 @@
-/* $Id: tiffinfo.c,v 1.25 2016-11-12 20:06:05 bfriesen Exp $ */
+/* $Id: tiffinfo.c,v 1.26 2016-12-03 14:18:49 erouault Exp $ */
 
 /*
  * Copyright (c) 1988-1997 Sam Leffler
@@ -417,7 +417,7 @@
 	uint64* stripbc=NULL;
 
 	TIFFGetField(tif, TIFFTAG_STRIPBYTECOUNTS, &stripbc);
-	if (nstrips > 0) {
+	if (stripbc != NULL && nstrips > 0) {
 		uint32 bufsize = (uint32) stripbc[0];
 		tdata_t buf = _TIFFmalloc(bufsize);
 		tstrip_t s;