From: Alexey Izbyshev <izbyshev@ispras.ru>
To: Szabolcs Nagy <nsz@port70.net>
Cc: musl@lists.openwall.com
Subject: Re: [musl] Potentially infinite loop in posix_spawn'ed child
Date: Mon, 24 May 2021 19:50:57 +0300 [thread overview]
Message-ID: <02a4eba412e82db36c06952bc8b81825@ispras.ru> (raw)
In-Reply-To: <20210524154014.GA790988@port70.net>
On 2021-05-24 18:40, Szabolcs Nagy wrote:
> * Alexey Izbyshev <izbyshev@ispras.ru> [2021-05-24 13:09:21 +0300]:
>> As an aside, perhaps it would make sense to call execve() in
>> posix_spawn()
>> implementation via a hidden symbol? This would both make it consistent
>> with
>> posix_spawnp() and avoid any trouble with user code executing in a
>> vfork'ed
>> child if execve() is overridden via e.g. LD_PRELOAD.
>
> libc symbols cannot be interposed by user code, they are
> all resolved within the libc, there should be no dynamic
> symbolic relocation in libc.so except for global data and
> malloc symbols (those are explicitly exported).
>
Thanks, I wasn't aware of musl's usage of --dynamic-list and thought
that weak aliases to hidden symbols (like "weak_alias(__pthread_exit,
pthread_exit)") are there to prevent interposition.
>> int execve(const char *path, char *const argv[], char *const envp[]) {
>
> this is only called with static linking, but that is not
> supportable usage: libc may provide execve and e.g. signal
> in the same object file and then there is a conflict
> because signal has to be linked. so this is just a user
> error.
>
I never intended this test case to be "supportable usage". This is just
a hack to make the problem with infinite loop reliably reproducible.
Alexey
next prev parent reply other threads:[~2021-05-24 16:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-24 10:09 Alexey Izbyshev
2021-05-24 15:40 ` Szabolcs Nagy
2021-05-24 16:50 ` Alexey Izbyshev [this message]
2021-05-24 20:33 ` Rich Felker
2021-05-25 6:30 ` Alexey Izbyshev
2021-05-25 14:32 ` Rich Felker
2024-02-29 14:03 ` Alexey Izbyshev
2024-02-29 15:35 ` Rich Felker
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