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http://bugzilla.maptools.org/show_bug.cgi?id=2596
From d7520d28685b96a28421ef01fb66cea8d1a96dfc Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Fri, 2 Dec 2016 21:56:56 +0000
Subject: [PATCH] * 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
---
ChangeLog | 7 +++++++
libtiff/tif_read.c | 4 ++--
libtiff/tiffiop.h | 6 +++++-
3 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/libtiff/tif_read.c b/libtiff/tif_read.c
index 80035929f033..29a311db0cb7 100644
--- a/libtiff/tif_read.c
+++ b/libtiff/tif_read.c
@@ -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 8bcd0c172c08..5294ee78ffaf 100644
--- a/libtiff/tiffiop.h
+++ b/libtiff/tiffiop.h
@@ -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)))
--
2.12.0
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