Bugzilla Bug 154573

GNU gv Stack Overflow Vulnerability


//----- Advisory


Program          : GNU gv
Homepage         : http://www.gnu.org/software/gv/
Tested version   : 3.6.2
Found by         : r.lifchitz at sysdream dot com
This advisory    : r.lifchitz at sysdream dot com
Discovery date   : 2006/11/06
Vendor notified  : 2006/11/09


//----- Application description


gv is a comfortable viewer of PostScript and PDF files for the X
Window System. It uses the ghostscript PostScript interpreter
and is based on the classic X front-end for gs, ghostview, which
it has replaced now.


//----- Description of vulnerability


The 'gv' viewer is prone to a remote stack overflow
vulnerability. This issue exists because the application fails
to perform proper boundary checks before copying user-supplied
data into process buffers. A remote attacker may execute arbitrary
code in the context of a user running the application. As a result,
the attacker can gain unauthorized access to the vulnerable computer.

This issue is present itself in the 'ps_gettext()' function residing
in the 'ps.c' file.

Long comments in some specific headers (such as '%%DocumentMedia:')
of PS files are unconditionally copied into 'text', a 257 character
buffer on the stack.

This issue is reported to affect gv 3.6.2, but earlier versions are
likely prone to this vulnerability as well. Applications using embedded
gv code may also be vulnerable.


//----- Proof Of Concept

[...]

/----- Solution


No known solution. You have to wait for a vendor upgrade and
be careful with unknown PS files.


//----- Impact


Successful exploitation leads to remote code execution.


//----- Credits


Renaud Lifchitz
r.lifchitz at sysdream dot com
http://www.sysdream.com/

SA22787

Created an attachment (id=101813) [edit]
gv-overflow.patch

Patch from Werner Fink.

fixed in 3.6.2-r1

Thx Stefan.

Arhces please test and mark stable. Target keywords are:

gv-3.6.2-r1.ebuild:KEYWORDS="alpha amd64 ~mips ppc ~ppc-macos ppc64 sparc x86"

x86 is the safest arch in the whole wide world.

ppc stable

SPARC stable

marked ppc64 stable

Works fine so far on amd64, worthy of the amd64 keyword.

Gentoo Base System version 1.12.6
Portage 2.1.1-r2 (default-linux/amd64/2006.1, gcc-4.1.1, glibc-2.4-r4,
2.6.17-gentoo-r8 x86_64)
=================================================================
System uname: 2.6.17-gentoo-r8 x86_64 AMD Athlon(tm) 64 Processor 3400+
Last Sync: Sun, 19 Nov 2006 23:30:01 +0000
app-admin/eselect-compiler: [Not Present]
dev-java/java-config: [Not Present]
dev-lang/python:     2.4.3-r4
dev-python/pycrypto: 2.0.1-r5
dev-util/ccache:     [Not Present]
dev-util/confcache:  [Not Present]
sys-apps/sandbox:    1.2.17
sys-devel/autoconf:  2.13, 2.60
sys-devel/automake:  1.4_p6, 1.5, 1.6.3, 1.7.9-r1, 1.8.5-r3, 1.9.6-r2
sys-devel/binutils:  2.16.1-r3
sys-devel/gcc-config: 1.3.13-r4
sys-devel/libtool:   1.5.22
virtual/os-headers:  2.6.11-r2
ACCEPT_KEYWORDS="amd64"
AUTOCLEAN="yes"
CBUILD="x86_64-pc-linux-gnu"
CFLAGS="-pipe -O3 -march=k8"
CHOST="x86_64-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/share/X11/xkb"
CONFIG_PROTECT_MASK="/etc/env.d /etc/gconf /etc/revdep-rebuild /etc/terminfo"
CXXFLAGS="-pipe -O3 -march=k8"
DISTDIR="/usr/portage/distfiles"
FEATURES="autoconfig distlocks metadata-transfer sandbox sfperms strict"
GENTOO_MIRRORS="http://distfiles.gentoo.org
http://distro.ibiblio.org/pub/linux/distributions/gentoo"
PKGDIR="/usr/portage/packages"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress
--force --whole-file --delete --delete-after --stats --timeout=180
--exclude='/distfiles' --exclude='/local' --exclude='/packages'"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
PORTDIR_OVERLAY="/usr/local/portage-etest"
SYNC="rsync://rsync.gentoo.org/gentoo-portage"
USE="amd64 X berkdb bitmap-fonts cli cracklib crypt cups debug dlloader dri
elibc_glibc fortran gdbm gpm iconv input_devices_keyboard input_devices_mouse
ipv6 isdnlog kernel_linux libg++ ncurses nls nptl nptlonly pam pcre perl ppds
pppd python readline reflection session spl ssl tcpd truetype-fonts type1-fonts
udev unicode userland_GNU video_cards_nvidia video_cards_vesa vorbis xorg zlib"
Unset:  CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LANG, LC_ALL, LDFLAGS,
LINGUAS, MAKEOPTS, PORTAGE_RSYNC_EXTRA_OPTS

amd64 stable

Stable on Alpha.

Thx Kloeri.

This one is ready for GLSA.

GLSA 200611-20

Seems like some distros are experiencing problems with the patch on x86_64
systems. I'll attach a better one.

Created an attachment (id=103114) [edit]
gv-CVE-2006-5864-better.patch

Proposed patch from SUSE.

Printing please check the new patch and report back.

No comments -> no problems? Closing for now. Feel free to reopen if you
disagree.