musl - Hangup calling setuid() from vfork() child

Message-ID: <CA+jjjYTJ0VXOf-z4tJspza0WzK8HxXCgFJ_XGtYgOdpMh4cSew@mail.gmail.com>
Date: Mon, 30 Sep 2019 08:29:16 -0700
From: Joshua Hudson <joshudson@...il.com>
To: musl@...ts.openwall.com
Subject: Hangup calling setuid() from vfork() child

If there is more than one thread and vfork() calls setuid(), musl libc hangs up.

void *thfunction(void*ig) {sleep(1000);returnNULL;}

int main()
{
    pthread_t id;
    pthread_create(&id, NULL, thfunction, NULL);
    if (vfork() == 0) {
        setuid(0); /* hangup */
        _exit(0);
    }
}

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