I've been contacted by a php user in the wild who told me that by simply issuing 'php -v', a semaphore that php opens for session management is not closed on exit.

This becomes bad news because the ipc system on linux is a global resource and not based per user, so it's possible for a local user to DOS the box by running php -v repeatidly.

[test@alpha3 test]$ ipcs > l
[test@alpha3 test]$ php -v
Content-type: text/html
4.1.2
[test@alpha3 test]$ ipcs > ll
[test@alpha3 test]$ diff l ll
9a10,11
> 0x00000000 65538      test      600        1         
> 0x00000000 98307      test      600        1         

I tried to trace this out between 4.1.2 and 4.2.2 (4.2.2 does not exhibit this behaviour) but I can find no obvious differances in the codepaths between versions. This behaviour seems to be present all the way back to 4.0.6 from the little additional checking I made.

Please see 
http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=71097
For a more detailed analysis

The RH 4.1.2 configure incantation:
./configure --prefix=/usr --with-config-file-path=/etc --enable-force-cgi-redirect --disable-debug --enable-pic --disable-rpath --enable-inline-optimization --with-bz2 --with-db3 --with-curl --with-dom=/usr --with-exec-dir=/usr/bin --with-freetype-dir=/usr --with-png-dir=/usr --with-gd --enable-gd-native-ttf --with-ttf --with-gdbm --with-gettext --with-ncurses --with-gmp --with-iconv --with-jpeg-dir=/usr --with-mm --with-openssl --with-png --with-pspell --with-regex=system --with-xml --with-expat-dir=/usr --with-zlib --with-layout=GNU --enable-bcmath --enable-debugger --enable-exif --enable-ftp --enable-magic-quotes --enable-safe-mode --enable-sockets --enable-sysvsem --enable-sysvshm --enable-discard-path --enable-track-vars --enable-trans-sid --enable-yp --enable-wddx --without-oci8 --with-imap=shared --with-imap-ssl --with-kerberos=/usr/kerberos --with-ldap=shared --with-mysql=shared,/usr --with-pgsql=shared --with-snmp=shared,/usr --with-snmp=shared --enable-ucd-snmp-hack --with-unixODBC=shared --enable-memory-limit --enable-bcmath --enable-shmop --enable-versioning --enable-calendar --enable-dbx --enable-dio --enable-mbstring --enable-mbstr-enc-trans --enable-force-cgi-redirect


Phil
=--=