Red Hat Bugzilla – Bug 1270524
systemd segfault in timer_enter_waiting while masking a unit
Last modified: 2016-12-20 09:56:41 EST
Description of problem: While trying to mask a timer file that in turn has a subunit override systemd segfaulted. Version-Release number of selected component (if applicable): systemd-219-24.fc22.x86_64 How reproducible: Reproducible every time. Steps to Reproduce: 1. Run rm /etc/systemd/system/dnf-makecache.timer.d/override.conf systemctl unmask dnf-makecache.timer reboot . 2. When the system is back up and running log in and run systemctl edit dnf-makecache.timer and put the following lines: [Timer] OnBootSec=10s OnUnitInactiveSec=1h and then save and quit your editor. 3. Run systemctl mask dnf-makecache.timer . Actual results: The following is printed: Broadcast message from systemd-journald@<hostname> (Sat 2015-10-10 15:31:20 UTC): systemd[1]: Caught <SEGV>, dumped core as pid 819. Broadcast message from systemd-journald@<hostname> (Sat 2015-10-10 15:31:20 UTC): systemd[1]: Freezing execution. and it is no longer possible to start/stop systemd units or change runlevels/reboot cleanly. Expected results: dnf-makecache.timer unit to be masked out? Additional info: Using echo "/tmp/core" > /proc/sys/kernel/core_pattern before step 3 allows a core dump to be produced. Looking at the backtrace in the coredump shows the following: #0 0x00007f433b062d07 in kill () from /lib64/libc.so.6 #1 0x0000563ce32c04dd in crash.lto_priv () #2 <signal handler called> #3 0x0000563ce337240c in timer_enter_waiting () #4 0x0000563ce3372d7d in timer_enter_waiting_coldplug () #5 0x0000563ce3386226 in manager_coldplug.lto_priv () #6 0x0000563ce32b8ef4 in manager_reload () #7 0x0000563ce32bb819 in main () systemd-219-20 seems to segfault with the same steps. I don't think this is security sensitive because I would imagine normal users would only crash their own systemd using these steps rather than the system one but I'll mark this private and someone can make it publically viewable after reviewing it.
dmesg also contains the following: [ 49.866897] systemd[1]: segfault at 1d0 ip 0000556629ef640c sp 00007ffffa39f700 error 4 in systemd[556629e1b000+14a000] [ 49.882635] systemd-coredum[820]: segfault at 0 ip 0000561607fb4361 sp 00007ffe6effbc90 error 6 in systemd-coredump[561607fa6000+18000]
This one is still here in systemd-222-8.fc23.x86_64 Can we make this issue public as I don't think anyone is going to look at it otherwise...
Filed upstream: https://github.com/systemd/systemd/issues/1981 .
Changing Fedora version back to 23 per comment #2,
This is now fixed in systemd v229 by https://github.com/poettering/systemd/commit/e903182e5b0daa941de47a9c08c824106cec7fe0 .
This bug was accidentally moved from POST to MODIFIED via an error in automation, please see mmccune@redhat.com with any questions
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