Re: [PATCH] wait_for_helper: SIGCHLD from user-space can lead touse-after-free

[Roland McGrath]

> Yes. kthreads run with all signal ignored, this is inherited from
> kthreadd() which does ignore_signal().

Ok.

> I don't think this can work. SIG_DFL for SIGCHLD is OK because it is
> sig_kernel_ignore(). But, say, SIGHUP and other signals still should
> be ignored, otherwise we have the same problems with the unwanted
> signal_pending() this patch tries to avoid.

Yes, I see.

> But even if we could do this,
> 
> > That should make it redundant in ____call_usermodehelper,
> > so it could be removed from there.
> 
> Please note that __call_usermodehelper() forks ____call_usermodehelper() too.

Ok.


Thanks,
Roland
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