CVE-2019-17546: Out-of-bounds Write (CWE-787)
value: tif_getimage.c in LibTIFF through 4.0.10, as used in GDAL through 3.0.1 and other products, has an integer overflow that potentially causes a heap-based buffer overflow via a crafted RGBA image, related to a "Negative-size-param" condition.
CWE description: The product writes data past the end, or before the beginning, of the intended buffer.
CVSS v3 base score: 8.8
Published: 2019-10-14T02:15Z
Repository: https://gitlab.com/libtiff/libtiff
Language: C
Files changed: libtiff/tif_getimage.c
Commit date: 2019-08-15 15:05:28 +0200
Commit message: 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

Diff: diff --git a/libtiff/tif_getimage.c b/libtiff/tif_getimage.c
index c88b5fa6..4da785d3 100644
--- a/libtiff/tif_getimage.c
+++ b/libtiff/tif_getimage.c
@@ -947,20 +947,27 @@ gtStripContig(TIFFRGBAImage* img, uint32* raster, uint32 w, uint32 h)
 
 	scanline = TIFFScanlineSize(tif);
 	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");
+			return 0;
+		}
 		if (_TIFFReadEncodedStripAndAllocBuffer(tif,
 		    TIFFComputeStrip(tif,row+img->row_offset, 0),
 		    (void**)(&buf),
                     maxstripsize,
-		    ((row + img->row_offset)%rowsperstrip + nrowsub) * scanline)==(tmsize_t)(-1)
+		    temp * scanline)==(tmsize_t)(-1)
 		    && (buf == NULL || img->stoponerr))
 		{
 			ret = 0;
 			break;
 		}
@@ -1049,19 +1056,26 @@ gtStripSeparate(TIFFRGBAImage* img, uint32* raster, uint32 w, uint32 h)
 	TIFFGetFieldDefaulted(tif, TIFFTAG_ROWSPERSTRIP, &rowsperstrip);
 	scanline = TIFFScanlineSize(tif);  
 	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");
+                        return 0;
+                }
                 if( buf == NULL )
                 {
                     if (_TIFFReadEncodedStripAndAllocBuffer(
                             tif, TIFFComputeStrip(tif, offset_row, 0),
                             (void**) &buf, bufsize,
-                            ((row + img->row_offset)%rowsperstrip + nrow) * scanline)==(tmsize_t)(-1)
+                            temp * scanline)==(tmsize_t)(-1)
                         && (buf == NULL || img->stoponerr))
                     {
                             ret = 0;
                             break;
                     }
@@ -1077,36 +1091,36 @@ gtStripSeparate(TIFFRGBAImage* img, uint32* raster, uint32 w, uint32 h)
                         p2 = p1 + stripsize;
                         pa = (alpha?(p2+stripsize):NULL);
                     }
                 }
 		else 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;
 			break;
 		}
 		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;
 			break;
 		}
 		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;
 			break;
 		}
 		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;
 				break;
 			}

Vulnerable code: 		    ((row + img->row_offset)%rowsperstrip + nrowsub) * scanline)==(tmsize_t)(-1)
                            ((row + img->row_offset)%rowsperstrip + nrow) * scanline)==(tmsize_t)(-1)
		    p0, ((row + img->row_offset)%rowsperstrip + nrow) * scanline)==(tmsize_t)(-1)
                                            p1, ((row + img->row_offset)%rowsperstrip + nrow) * scanline) == (tmsize_t)(-1)
                                            p2, ((row + img->row_offset)%rowsperstrip + nrow) * scanline) == (tmsize_t)(-1)
			    pa, ((row + img->row_offset)%rowsperstrip + nrow) * scanline)==(tmsize_t)(-1)
Fixed code: 		uint32 temp;
		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");
			return 0;
		}
		    temp * scanline)==(tmsize_t)(-1)
                uint32 temp;
                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");
                        return 0;
                }
                            temp * scanline)==(tmsize_t)(-1)
		    p0, temp * scanline)==(tmsize_t)(-1)
                                            p1, temp * scanline) == (tmsize_t)(-1)
                                            p2, temp * scanline) == (tmsize_t)(-1)
			    pa, temp * scanline)==(tmsize_t)(-1)