Bug#813879: systemd: Assertion 's->exec_command[SERVICE_EXEC_START]' failed service_enter_start()

[Alexandre Detiste]

Le lundi 8 février 2016, 18:18:20 Yuriy M. Kaminskiy a écrit :

> Problem is, we started executing unit, spawned StartPre command, then 
> unit file was removed, systemctl daemon-reload was issued, unit 
> structure become half-ghost, then we got SIGCHLD for that StartPre 
> command from the already-removed unit. Oops.

The half-ghost issue is the reason the two commands are
"encapsulated" in a single 'sh -c' call.

Without that the second call simply vanish.

cron-after-var.service is even weirder;
it's just the least worst way to do it.


> 
> With 96fb824 applied, end result would be same:
> 
> @@ -1332,6 +1345,12 @@ static void service_enter_start(Service *s) {
>                   c = s->main_command = s->exec_command[SERVICE_EXEC_START];
>           }
> 
> +        if (!c) {
> +                assert(s->type == SERVICE_ONESHOT);
> +                service_enter_start_post(s);
> +                return;
> +        }
> +
> 
> c is NULL, s->type here is _SERVICE_TYPE_INVALID, so we'll die in assert 
> anyway :-\
> 
> It is possible that upstream systemd version is still affected, you may 
> want to try install jessie's systemd-cron 1.3.* into sid and play with 
> install/removal in a loop.

A long time ago running systemctl daemon-reload in a loop was just enough to crash systemd.

And doing a big update will leads to so many calls to daemon-reload anyway.

> Completely untested patches for systemd master and backport to v215 is 
> attached.