oss-sec mailing list archives
Re: glibc crypt(3), crypt_r(3), PHP crypt() may use alloca()
From: Steve Grubb <sgrubb () redhat com>
Date: Wed, 2 May 2012 08:12:50 -0400
On Wednesday, May 02, 2012 01:21:32 AM Solar Designer wrote:
On Fri, Mar 30, 2012 at 11:05:32PM +0400, Solar Designer wrote:On Fri, Mar 30, 2012 at 12:47:54PM -0600, Jeff Law wrote:On 03/30/2012 12:43 PM, Solar Designer wrote:Do you realize that plenty of services that use crypt() - likely the majority of them, even - don't handle NULL returns, so they will segfault when these conditions are triggered?Then, IMHO, the app is clearly broken. Crypt has been defined as potentially returning NULL and at least for glibc has done so since the introduction of sha256/sha512, if the app fails to check for that, then the app needs to be fixed.Sure. I am not arguing against fixing the apps (in fact, I am planning to fix one of mine - code originally written in 1998 or so - regardless of what glibc does on this), but I am arguing for not having glibc expose the problem. Considering the age of Unix, SUSv2 and POSIX.1-2001 are fairly recent (I think this may be when the NULL returns were first standardized), and glibc's SHA-crypt is very young. It still makes sense to support apps older than that, including without changes.Paul Wouters (Red Hat) has started to fix the apps: https://mobile.twitter.com/letoams/status/195181246614224896 "sent crypt() NULL patches out for apg control-center cyrus-sasl openssh pam passwdqc ppp python screen shadow-utils sysvinit-tools yp-tools 7 days ago"
I gave Paul the following script to help locate anything that could be affected. Maybe it is useful to find software we are not shipping? It does have an rpm dependency, but you can switch that out to whatever you use for packaging. -Steve #!/bin/sh # This program takes directories as input and looks for programs # that use the crypt function of glibc libdirs="/lib /lib64 /usr/lib /usr/lib64" progdirs="/bin /sbin /usr/bin /usr/sbin /usr/libexec" FOUND=0 check() { x=`readelf -s $1 2>/dev/null | grep crypt@.*GLIBC` if [ x"$x" != "x" ] ; then FOUND=1 package=`rpm -qf --queryformat "%{NAME}-%{VERSION}" $1 2>/dev/null` if [ $? -eq 1 ] ; then package="Not Owned" fi ls -l $1 | awk '{ printf "%-50s %s\n", $9, p} ' p="$package" fi } scan () { if [ "$1" = "1" ] ; then dirs=$libdirs elif [ "$1" = "2" ] ; then dirs=$progdirs elif [ "$1" = "3" ] ; then dirs=$3 fi for d in $dirs ; do if [ ! -d $d ] ; then continue fi files=`/usr/bin/find $d -name "$2" -type f 2>/dev/null` for f in $files do check $f done done } if [ $# -eq 1 ] ; then if [ -d $1 ] ; then scan 3 '*' $1 else echo "Input is not a directory" exit 1 fi else scan 1 '*.so' scan 2 '*' fi if [ $FOUND -eq 0 ] ; then # Nothing to report, just exit echo "No problems found" 1>&2 exit 0 fi exit 1
Current thread:
- Re: glibc crypt(3), crypt_r(3), PHP crypt() may use alloca() Solar Designer (May 01)
- Re: glibc crypt(3), crypt_r(3), PHP crypt() may use alloca() Steve Grubb (May 02)