Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 22 Oct 2001 12:19:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 22 Oct 2001 12:18:54 -0400 Received: from e21.nc.us.ibm.com ([32.97.136.227]:45263 "EHLO e21.nc.us.ibm.com") by vger.kernel.org with ESMTP id ; Mon, 22 Oct 2001 12:18:46 -0400 Date: Mon, 22 Oct 2001 11:18:59 -0500 From: Dave McCracken To: Linus Torvalds , Linux Kernel Subject: [PATCH] Fix broken reparenting in forget_original_parent() (resubmit) Message-ID: <62470000.1003767539@baldur> X-Mailer: Mulberry/2.1.0 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; FORMAT=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org The code in forget_original_parent() that attempts to reparent a task to another task in the thread group is broken. It's not safe to parent to any task other than init because of the race condition it introduces (init is only safe as long as it never dies, in fact). The patch to change forget_original_parent() to always use init is below. Dave McCracken ====================================================================== Dave McCracken IBM Linux Base Kernel Team 1-512-838-3059 dmccr@us.ibm.com T/L 678-3059 --------------------- --- linux-2.4.12/kernel/exit.c Mon Sep 10 15:04:33 2001 +++ linux-2.4.12-signal-kdb/kernel/exit.c Thu Oct 18 11:31:57 2001 @@ -149,28 +149,21 @@ } /* - * When we die, we re-parent all our children. - * Try to give them to another thread in our process - * group, and if no such member exists, give it to + * When we die, we re-parent all our children to * the global child reaper process (ie "init") */ static inline void forget_original_parent(struct task_struct * father) { - struct task_struct * p, *reaper; + struct task_struct * p; read_lock(&tasklist_lock); - /* Next in our thread group */ - reaper = next_thread(father); - if (reaper == father) - reaper = child_reaper; - for_each_task(p) { if (p->p_opptr == father) { /* We dont want people slaying init */ p->exit_signal = SIGCHLD; p->self_exec_id++; - p->p_opptr = reaper; + p->p_opptr = child_reaper; if (p->pdeath_signal) send_sig(p->pdeath_signal, p, 0); } } ====================================================================== Dave McCracken IBM Linux Base Kernel Team 1-512-838-3059 dmccr@us.ibm.com T/L 678-3059 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/