After logout (using xfwm4, did not test other X environments), xdm crashes with a segfault. The stacktrace indicates, that this happens while pam tries to write a logout message to syslog. However, pam has not changed since march and did not show this misbehaviour before updating to xdm 1.1.9. Switching back to 1.1.8 while leaving the config files unchanged (esp. the authdir, which was changed when updating to 1.1.9) solves the problem. Reproducible: Always Steps to Reproduce: 1. logout from X user session 2. Actual Results: Screen turns black or switches to tty1 Expected Results: The xdm login screen appears syslog output: Oct 5 21:53:48 ardbeg xdm[18380]: pam_unix(xdm:session): session opened for user tom by tom(uid=0) Oct 5 21:53:56 ardbeg xdm[18380]: segfault at 7f01113eb611 ip 00007f0111668180 sp 00007ffff9c1f3d8 error 4 in libc-2.9.so[7f01115ee000+14a000] Oct 5 21:53:56 ardbeg HDMI hot plug event: Presence_Detect=0 ELD_Valid=0 Oct 5 21:53:56 ardbeg [drm:i915_get_vblank_counter] *ERROR* trying to get vblank count for disabled pipe 1 Oct 5 21:53:56 ardbeg mtrr: no MTRR for d0000000,10000000 found emerge --info: Portage 2.1.6.13 (default/linux/amd64/2008.0, gcc-4.3.4, glibc-2.9_p20081201-r2, 2.6.30-gentoo-r5 x86_64) ================================================================= System uname: Linux-2.6.30-gentoo-r5-x86_64-Intel-R-_Core-TM-2_Quad_CPU_Q9550_@_2.83GHz-with-gentoo-1.12.11.1 Timestamp of tree: Mon, 05 Oct 2009 16:30:02 +0000 app-shells/bash: 4.0_p28 dev-java/java-config: 2.1.8-r1 dev-lang/python: 2.6.2-r1 sys-apps/baselayout: 1.12.11.1 sys-apps/sandbox: 1.6-r2 sys-devel/autoconf: 2.13, 2.63-r1 sys-devel/automake: 1.8.5-r3, 1.9.6-r2, 1.10.2 sys-devel/binutils: 2.18-r3 sys-devel/gcc-config: 1.4.1 sys-devel/libtool: 2.2.6a virtual/os-headers: 2.6.27-r2 ACCEPT_KEYWORDS="amd64" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-O2 -fno-strict-aliasing -march=core2 -msse4.1 -pipe" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /var/lib/hsqldb" CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/env.d /etc/env.d/java/ /etc/fonts/fonts.conf /etc/gconf /etc/init.d /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo /etc/udev/rules.d" CXXFLAGS="-O2 -fno-strict-aliasing -march=core2 -msse4.1 -pipe" DISTDIR="/home/distfiles" FEATURES="distlocks fixpackages parallel-fetch protect-owned sandbox sfperms strict unmerge-orphans userfetch" GENTOO_MIRRORS="http://linux.rz.ruhr-uni-bochum.de/download/gentoo-mirror http://ftp.uni-erlangen.de/pub/mirrors/gentoo ftp://ftp.join.uni-muenster.de/pub/linux/distributions/gentoo ftp://ftp.wh2.tu-dresden.de/pub/mirrors/gentoo http://mirrors.sec.informatik.tu-darmstadt.de/gentoo http://ftp-stud.fht-esslingen.de/pub/Mirrors/gentoo" LANG="de_DE" LDFLAGS="-Wl,-O1" LINGUAS="de de_DE en en_US en_GB" MAKEOPTS="-j4" PKGDIR="/usr/portage/packages" PORTAGE_CONFIGROOT="/" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --stats --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages" PORTAGE_TMPDIR="/tmp" PORTDIR="/usr/portage" SYNC="rsync://rsync.gentoo.org/gentoo-portage" USE="X a52 aac acpi alsa amd64 berkdb bzip2 cairo cdda cddax cddb cdio cdr cli consolekit cracklib crypt cups curl dbus dri dts dvd dvdr emacs exif expat faac faad ffmpeg flac fontconfig fortran gd gdbm gif gimp gmp gnome gnome-keyring gnutls graphviz gs gstreamer gtk hal iconv isdnlog ithreads java jpeg jpeg2k lcms libgcrypt libnotify lm_sensors log4j logrotate lzma mad mmx mng modules mp3 mpeg mudflap multilib mysql ncurses netpbm nls nptl nptlonly nsplugin ogg opengl openmp pam pcre perl png ppds pppd python raw readline reflection sdl session smp sndfile spl sse sse2 ssl svg sysfs tcpd threads thunar tiff truetype unicode v4l v4l2 vim-syntax vorbis x264 xcomposite xml xorg xpm xulrunner xv zlib" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mmap_emul mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" ELIBC="glibc" INPUT_DEVICES="evdev keyboard mouse" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="de de_DE en en_US en_GB" USERLAND="GNU" VIDEO_CARDS="intel v4l" Unset: CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, FFLAGS, INSTALL_MASK, LC_ALL, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, PORTDIR_OVERLAY
I see this too, on two different x86 hosts with two different display cards (Intel 815 and ATI Radeon). It began when I ran the looong list of updates for the recently released xorg 1.6 ebuilds. On one host I noticed that the current newest xorg-server ebuild was the 1.6.3-901-r2 release candidate (since it was writing "this is experimental, we don't support it" messages in its log!). I used ACCEPT_KEYWORDS to allow 1.6.4 (an actual X.Org release version) to install, but it didn't affect the problem. Seeing the mention of PAM here, I found a couple of third-party PAM modules that were older than the most recent PAM install, and reinstalled them (pam_krb5, consolekit), again without relief.
I can confirm this behavior, having just installed xorg-server-7.4 last night and had to back out xdm this morning. I'm using fvwm2 rather than xfwm4, but I don't believe that the wm is significant here. xdm-1.1.9 also dies if an invalid username/password combination is entered.
I confirm this bug. I use xrog-server-1.6.3.901-r2. After I log out and xdm stops I find a message like these below in dmesg (one message per logout). xdm[15546]: segfault at 7fa976b3d021 ip 00007fa976fd1fd0 sp 00007fff168c6bf8 error 4 in libc-2.9.so[7fa976f57000+14b000] xdm[15672]: segfault at 7f004d712021 ip 00007f004dba6fd0 sp 00007fff088ecf28 error 4 in libc-2.9.so[7f004db2c000+14b000] xdm[15856]: segfault at 7f327f82e021 ip 00007f327fcc2fd0 sp 00007fff8aef4928 error 4 in libc-2.9.so[7f327fc48000+14b000] xdm-1.1.8 works fine.
*** This bug has been marked as a duplicate of bug 286923 ***
The history of bug 286923 seems to mention two seperate bugs: the initially mentioned bug related to kerberos during _login_ and the one mentioned later on during _logout_ (or failed login) not related to kerberos. Just because both bugs cause a segfault in the same program does not mean, it is the same bug. The bug here is probably a duplicate of the latter one, but to keep different bugs seperately, i think it deserves its own bugzilla entry and suggest reopening it. BTW: i consider this being a major bug (users not having root access are unable to login after logout) and i was really astonished that it didn't show up during QA of X11 7.4. Is there any known configuration where xdm survives a logout?
In any case, xdm is not a priority for the X11 team (upstream isn't really working much on it either...) and bugs will have to be filed upstream for this to be properly fixed. Like always, please paste the url here or in the duped bug so I can track the bug and apply patches to our ebuilds. Thanks
Could you guys post whether this upstream patch which just landed in the git tree helped your issues? http://bugs.freedesktop.org/show_bug.cgi?id=24589
