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Message-ID: <20220627083737.GW1320090@port70.net>
Date: Mon, 27 Jun 2022 10:37:37 +0200
From: Szabolcs Nagy <nsz@...t70.net>
To: Florian Weimer <fweimer@...hat.com>
Cc: Nick Peng <pymumu@...il.com>, musl@...ts.openwall.com
Subject: Re: BUG: Calling readdir/dirfd after vfork will cause
deadlock.
* Florian Weimer <fweimer@...hat.com> [2022-06-27 09:42:57 +0200]:
> * Szabolcs Nagy:
>
> > * Nick Peng <pymumu@...il.com> [2022-06-25 11:40:17 +0800]:
> >> Description: After vfork, calling functions such as readdir/dirfd may
> >> cause deadlock. GNU C is OK.
> >
> > why do you think "GNU C is OK"? is this from some real software?
>
> glibc supports opendir/readdir/closedir after vfork as an extension.
> The JVM depends on it.
how does that work? i think glibc just calls vfork syscall (or
clone(CLONE_VM|CLONE_VFORK)) from asm and opendir allocates.
so i'd expect a deadlock where the parent waits for the child
to exec while holding the malloc lock.
>
> Of course it's undefined, but I really see no way around keeping support
> for it for the time being.
>
> Thanks,
> Florian
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