On 04/11, Bill Davidsen wrote:
>
> Oleg Nesterov wrote:
> >On 04/10, Eric W. Biederman wrote:
> >
> >>I'm trying to remember what the story is now. There is a nasty
> >>race somewhere with reparenting, a threaded parent setting SIGCHLD to
> >>SIGIGN, and non-default signals that results in an zombie that no one
> >>can wait for and reap. It requires being reparented twice to trigger.
> >
> >reparent_thread:
> >
> > ...
> >
> > /* If we'd notified the old parent about this child's death,
> > * also notify the new parent.
> > */
> > if (!traced && p->exit_state == EXIT_ZOMBIE &&
> > p->exit_signal != -1 && thread_group_empty(p))
> > do_notify_parent(p, p->exit_signal);
> >
> >We notified /sbin/init. If it ignores SIGCHLD, we should release the task.
> >We don't do this.
> >
> >The best fix I believe is to cleanup the
> >forget_original_parent/reparent_thread
> >interaction and factor out this "exit_state == EXIT_ZOMBIE && exit_signal
> >== -1"
> >checks.
> >
> As long as the original parent is preserved for getppid(). There are
> programs out there which communicate between the parent and child with
> signals, and if the original parent dies, it undesirable to have the
> child getppid() and start sending signals to a program not expecting
> them. Invites undefined behavior.
Sorry, can't understand.
If p->exit_signal == -1 after do_notify_parent() above, the task is completely
dead. Nobody can release it, we should do this (if EXIT_ZOMBIE). At this point
"p" was already re-parented, but this (and getppid) doesn't matter at all.
OK. Most likely you meant something else. Could you clarify?
Oleg.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
