Date: Wed, 15 Jun 2016 12:05:47 +0200 From: Marcus Meissner <meissner@...e.de> To: oss-security@...ts.openwall.com Subject: Re: CVE-2016-5323: libtiff 4.0.6 tiffcrop _TIFFFax3fillruns(): divide by zero Hi, This looks like a NULL pointer dereference, not a division by 0. Ciao, Marcus On Wed, Jun 15, 2016 at 02:37:11AM +0000, 张开翔 wrote: > Details > ======= > > Product: libtiff > Affected Versions: <= 4.0.6 > Vulnerability Type: divide by zero > Vendor URL: http://www.remotesensing.org/libtiff/ > Credit: Kaixiang Zhang of the Cloud Security Team, Qihoo 360 > CVE ID: CVE-2016-5323 > Tested system version: > fedora23 32bit > fedora23 64bit > CentOS Linux release 7.1.1503 64bit > > Introduction > ======= > > t was always corrupted when I use tiffcrop command followed by a crafted TIFF image in function _TIFFFax3fillruns () without checking the value of divisor, it causes a divide by zero flaw. Attackers cound exploit this issue to cause denial-of-service. > > Here is the stack info: > gdb –args ./tiffcrop _TIFFFax3fillruns.tif tmpout.tif > --- --- > Program received signal SIGSEGV, Segmentation fault. > 0x00007ffff7ad97f0 in _TIFFFax3fillruns (buf=0x0, runs=0x673500, erun=<optimized out>, lastx=64) at tif_fax3.c:407 > 407 ZERO(n, cp); > (gdb) bt > #0 0x00007ffff7ad97f0 in _TIFFFax3fillruns (buf=0x0, runs=0x673500, erun=<optimized out>, lastx=64) at tif_fax3.c:407 > #1 0x00007ffff7ae087c in Fax3DecodeRLE (tif=0x662010, buf=0x0, occ=8192, s=<optimized out>) at tif_fax3.c:1527 > #2 0x00007ffff7ba3739 in TIFFReadEncodedTile (tif=tif@...ry=0x662010, tile=8, buf=0x0, size=8192, size@...ry=-1) at tif_read.c:668 > #3 0x00007ffff7ba3a01 in TIFFReadTile (tif=tif@...ry=0x662010, buf=<optimized out>, x=x@...ry=0, y=y@...ry=0, z=z@...ry=0, s=s@...ry=8) at tif_read.c:641 > #4 0x0000000000443e41 in readSeparateTilesIntoBuffer (bps=1, spp=129, tl=1024, tw=64, imagewidth=32, imagelength=32, obuf=0x7ffff7ee5010 "", in=0x662010) at tiffcrop.c:994 > #5 loadImage (in=in@...ry=0x662010, image=image@...ry=0x7fffffff7960, dump=dump@...ry=0x7fffffffc270, read_ptr=read_ptr@...ry=0x7fffffff7920) at tiffcrop.c:6079 > #6 0x0000000000403209 in main (argc=<optimized out>, argv=<optimized out>) at tiffcrop.c:2278 > (gdb) p cp > $2 = (unsigned char *) 0x0 > > -- Marcus Meissner,SUSE LINUX GmbH; Maxfeldstrasse 5; D-90409 Nuernberg; Zi. 3.1-33,+49-911-740 53-432,,serv=loki,mail=wotan,type=real <meissner@...e.de>
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