Bug#498678: sigdie must not be called from a signal handler context

[Florian Weimer <fw@deneb.enyo.de>]

Package: openssh-server
Version: 4.3p2-9etch2

This code:

void
sigdie(const char *fmt,...)
{
        va_list args;

        va_start(args, fmt);
        do_log(SYSLOG_LEVEL_FATAL, fmt, args);
        va_end(args);
        _exit(1);
}

is not safe to call from signal handlers (mainly due to snprintf-type
formatting and syslog calls in do_log).  However, it is called from a
signal handler in sshd.c:

/*
 * Signal handler for the alarm after the login grace period has expired.
 */
static void
grace_alarm_handler(int sig)
{
        if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
                kill(pmonitor->m_pid, SIGALRM);

        /* Log error and exit. */
        sigdie("Timeout before authentication for %s", get_remote_ipaddr());
}