From 7a05de95bf761c4c2a9e409abd443b0c2c1d0ab7 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Thu, 15 Aug 2019 15:05:28 +0200
Subject: [PATCH] RGBA interface: fix integer overflow potentially causing
 write heap buffer overflow, especially on 32 bit builds. Fixes
 https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=16443. Credit to OSS
 Fuzz

---
 libtiff/tif_getimage.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/libtiff/tif_getimage.c b/libtiff/tif_getimage.c
index c664cc0..4c79479 100644
--- a/libtiff/tif_getimage.c
+++ b/libtiff/tif_getimage.c
@@ -889,15 +889,23 @@ gtStripContig(TIFFRGBAImage* img, uint32* raster, uint32 w, uint32 h)
 	fromskew = (w < imagewidth ? imagewidth - w : 0);
 	for (row = 0; row < h; row += nrow)
 	{
+		uint32 temp;
 		rowstoread = rowsperstrip - (row + img->row_offset) % rowsperstrip;
 		nrow = (row + rowstoread > h ? h - row : rowstoread);
 		nrowsub = nrow;
 		if ((nrowsub%subsamplingver)!=0)
 			nrowsub+=subsamplingver-nrowsub%subsamplingver;
+		temp = (row + img->row_offset)%rowsperstrip + nrowsub;
+		if( scanline > 0 && temp > (size_t)(TIFF_TMSIZE_T_MAX / scanline) )
+		{
+			TIFFErrorExt(tif->tif_clientdata, TIFFFileName(tif), "Integer overflow in gtStripContig");
+			_TIFFfree(buf);
+			return 0;
+		}
 		if (TIFFReadEncodedStrip(tif,
 		    TIFFComputeStrip(tif,row+img->row_offset, 0),
 		    buf,
-		    ((row + img->row_offset)%rowsperstrip + nrowsub) * scanline)==(tmsize_t)(-1)
+		    temp * scanline)==(tmsize_t)(-1)
 		    && img->stoponerr)
 		{
 			ret = 0;
@@ -997,11 +1005,19 @@ gtStripSeparate(TIFFRGBAImage* img, uint32* raster, uint32 w, uint32 h)
 	fromskew = (w < imagewidth ? imagewidth - w : 0);
 	for (row = 0; row < h; row += nrow)
 	{
+		uint32 temp;
 		rowstoread = rowsperstrip - (row + img->row_offset) % rowsperstrip;
 		nrow = (row + rowstoread > h ? h - row : rowstoread);
 		offset_row = row + img->row_offset;
+		temp = (row + img->row_offset)%rowsperstrip + nrow;
+		if( scanline > 0 && temp > (size_t)(TIFF_TMSIZE_T_MAX / scanline) )
+		{
+			TIFFErrorExt(tif->tif_clientdata, TIFFFileName(tif), "Integer overflow in gtStripSeparate");
+			_TIFFfree(buf);
+			return 0;
+		}
 		if (TIFFReadEncodedStrip(tif, TIFFComputeStrip(tif, offset_row, 0),
-		    p0, ((row + img->row_offset)%rowsperstrip + nrow) * scanline)==(tmsize_t)(-1)
+		    p0, temp * scanline)==(tmsize_t)(-1)
 		    && img->stoponerr)
 		{
 			ret = 0;
@@ -1009,7 +1025,7 @@ gtStripSeparate(TIFFRGBAImage* img, uint32* raster, uint32 w, uint32 h)
 		}
 		if (colorchannels > 1 
                     && TIFFReadEncodedStrip(tif, TIFFComputeStrip(tif, offset_row, 1),
-                                            p1, ((row + img->row_offset)%rowsperstrip + nrow) * scanline) == (tmsize_t)(-1)
+                                            p1, temp * scanline) == (tmsize_t)(-1)
 		    && img->stoponerr)
 		{
 			ret = 0;
@@ -1017,7 +1033,7 @@ gtStripSeparate(TIFFRGBAImage* img, uint32* raster, uint32 w, uint32 h)
 		}
 		if (colorchannels > 1 
                     && TIFFReadEncodedStrip(tif, TIFFComputeStrip(tif, offset_row, 2),
-                                            p2, ((row + img->row_offset)%rowsperstrip + nrow) * scanline) == (tmsize_t)(-1)
+                                            p2, temp * scanline) == (tmsize_t)(-1)
 		    && img->stoponerr)
 		{
 			ret = 0;
@@ -1026,7 +1042,7 @@ gtStripSeparate(TIFFRGBAImage* img, uint32* raster, uint32 w, uint32 h)
 		if (alpha)
 		{
 			if (TIFFReadEncodedStrip(tif, TIFFComputeStrip(tif, offset_row, colorchannels),
-			    pa, ((row + img->row_offset)%rowsperstrip + nrow) * scanline)==(tmsize_t)(-1)
+			    pa, temp * scanline)==(tmsize_t)(-1)
 			    && img->stoponerr)
 			{
 				ret = 0;
-- 
2.26.0.rc2