commit 8c101323f5789ef6a0db952d53794e9c4ba48207
Author: erouault <erouault>
Date:   Fri Dec 2 21:56:56 2016 +0000

    * libtiff/tif_read.c, libtiff/tiffiop.h: fix uint32 overflow in
    TIFFReadEncodedStrip() that caused an integer division by zero.
    Reported by Agostino Sarubbo.
    Fixes http://bugzilla.maptools.org/show_bug.cgi?id=2596

diff --git a/ChangeLog b/ChangeLog
index 46a5d7c..668b66a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2016-12-02 Even Rouault <even.rouault at spatialys.com>
+
+	* libtiff/tif_read.c, libtiff/tiffiop.h: fix uint32 overflow in
+	TIFFReadEncodedStrip() that caused an integer division by zero.
+	Reported by Agostino Sarubbo.
+	Fixes http://bugzilla.maptools.org/show_bug.cgi?id=2596
+
 2016-11-19  Bob Friesenhahn  <bfriesen@simple.dallas.tx.us>
 
 	* libtiff 4.0.7 released.
diff --git a/libtiff/tif_read.c b/libtiff/tif_read.c
index 8003592..29a311d 100644
--- a/libtiff/tif_read.c
+++ b/libtiff/tif_read.c
@@ -1,4 +1,4 @@
-/* $Id: tif_read.c,v 1.49 2016-07-10 18:00:21 erouault Exp $ */
+/* $Id: tif_read.c,v 1.50 2016-12-02 21:56:56 erouault Exp $ */
 
 /*
  * Copyright (c) 1988-1997 Sam Leffler
@@ -346,7 +346,7 @@ TIFFReadEncodedStrip(TIFF* tif, uint32 strip, void* buf, tmsize_t size)
 	rowsperstrip=td->td_rowsperstrip;
 	if (rowsperstrip>td->td_imagelength)
 		rowsperstrip=td->td_imagelength;
-	stripsperplane=((td->td_imagelength+rowsperstrip-1)/rowsperstrip);
+	stripsperplane= TIFFhowmany_32_maxuint_compat(td->td_imagelength, rowsperstrip);
 	stripinplane=(strip%stripsperplane);
 	plane=(uint16)(strip/stripsperplane);
 	rows=td->td_imagelength-stripinplane*rowsperstrip;
diff --git a/libtiff/tiffiop.h b/libtiff/tiffiop.h
index 8bcd0c1..5294ee7 100644
--- a/libtiff/tiffiop.h
+++ b/libtiff/tiffiop.h
@@ -1,4 +1,4 @@
-/* $Id: tiffiop.h,v 1.89 2016-01-23 21:20:34 erouault Exp $ */
+/* $Id: tiffiop.h,v 1.90 2016-12-02 21:56:56 erouault Exp $ */
 
 /*
  * Copyright (c) 1988-1997 Sam Leffler
@@ -250,6 +250,10 @@ struct tiff {
 #define TIFFhowmany_32(x, y) (((uint32)x < (0xffffffff - (uint32)(y-1))) ? \
 			   ((((uint32)(x))+(((uint32)(y))-1))/((uint32)(y))) : \
 			   0U)
+/* Variant of TIFFhowmany_32() that doesn't return 0 if x close to MAXUINT. */
+/* Caution: TIFFhowmany_32_maxuint_compat(x,y)*y might overflow */
+#define TIFFhowmany_32_maxuint_compat(x, y) \
+			   (((uint32)(x) / (uint32)(y)) + ((((uint32)(x) % (uint32)(y)) != 0) ? 1 : 0))
 #define TIFFhowmany8_32(x) (((x)&0x07)?((uint32)(x)>>3)+1:(uint32)(x)>>3)
 #define TIFFroundup_32(x, y) (TIFFhowmany_32(x,y)*(y))
 #define TIFFhowmany_64(x, y) ((((uint64)(x))+(((uint64)(y))-1))/((uint64)(y)))