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Date: Fri, 25 Dec 2015 13:30:48 +0300
From: Solar Designer <solar@...nwall.com>
To: oss-security@...ts.openwall.com
Subject: Re: CVE request libtiff: out-of-bounds read in CIE Lab image format
Hi,
Unfortunately, the text/plain version of zzf's message was badly
misformatted. I've included below the result of processing of the
text/html portion, which is actually readable.
Alexander
zuozhi.fzz@...baba-inc.com wrote:
> If the data of image is packed(e.g., TIFFDirectory.td_samplesperpixel == 1,
> TIFFDirectory.td_bitspersample == 8), a pixel only owns one byte. But in the
> implementation of putcontig8bitCIELab, it eats 3 bytes per pixel. This will
> lead to an out-of-bounds read vulnerability.
>
> vuln code in tif_getimage.c, libtiff v4.0.6
>
> 1699 DECLAREContigPutFunc(putcontig8bitCIELab)
> 1700 {
> 1701 float X, Y, Z;
> 1702 uint32 r, g, b;
> 1703 (void) y;
> 1704 fromskew *= 3;
> 1705 while (h-- > 0) {
> 1706 for (x = w; x-- > 0;) {
> 1707 TIFFCIELabToXYZ(img->cielab,
> 1708 (unsigned char)pp[0],
> 1709 (signed char)pp[1],
> 1710 (signed char)pp[2],
> 1711 &X, &Y, &Z);
> 1712 TIFFXYZToRGB(img->cielab, X, Y, Z, &r, &g, &b);
> 1713 *cp++ = PACK(r, g, b);
> 1714 pp += 3;
> 1715 }
> 1716 cp += toskew;
> 1717 pp += fromskew;
> 1718 }
> 1719 }
>
> I use the tutorial code from http://www.remotesensing.org/libtiff/libtiff.html
> to test that, and poc is in the attachment.
>
> #include "tiffio.h"
> main(int argc, char* argv[])
> {
> TIFF* tif = TIFFOpen(argv[1], "r");
> if (tif) {
> TIFFRGBAImage img;
> char emsg[1024];
>
> if (TIFFRGBAImageBegin(&img, tif, 0, emsg)) {
> size_t npixels;
> uint32* raster;
>
> npixels = img.width * img.height;
> raster = (uint32*) _TIFFmalloc(npixels * sizeof (uint32));
> if (raster != NULL) {
> if (TIFFRGBAImageGet(&img, raster, img.width, img.height)) {
> ...process raster data...
> }
> _TIFFfree(raster);
> }
> TIFFRGBAImageEnd(&img);
> } else
> TIFFError(argv[1], emsg);
> TIFFClose(tif);
> }
> exit(0);
> }
>
> If it would be assigned a CVE, please credit it for: zzf of Alibaba.
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