From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2738C4741F for ; Mon, 9 Nov 2020 13:43:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6DF7C206E3 for ; Mon, 9 Nov 2020 13:43:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604929437; bh=qeSrkBmiZcQS34gC7q9vn3RhXPLvkmwmfXrBkQ38DWs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=lB2yaN+LfID6nOglaydMQTfltp9qAFGZdAZTEO2VvGiA/51RKzv/9AKKQeIqs7WFe YbFyYigL7s9B8qtgKmAJ3iiM6HqATXoV2qGl1cWSg9ILTNYr7c/epDEtz++VobZtkX uAheLl0slEhsjeF0NqOGWPWoJerFrgFapn4F3QRw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730374AbgKINn4 (ORCPT ); Mon, 9 Nov 2020 08:43:56 -0500 Received: from mail.kernel.org ([198.145.29.99]:53854 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730377AbgKIM7e (ORCPT ); Mon, 9 Nov 2020 07:59:34 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 49B42221F9; Mon, 9 Nov 2020 12:59:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604926773; bh=qeSrkBmiZcQS34gC7q9vn3RhXPLvkmwmfXrBkQ38DWs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nkfYbqcuy44/bHa9+Ot0ZD1jEIsmQ20cSdnA81ywmwA4c+RlS5Jh2DpfyFbTy5s3g KEXscWU/TkdebJ3r7pLVUNDLeLEJogPwK4eag5lRwvQd3rLGVMHurlr7bkbLqIRtzQ CqYQ1K5FGChH139qf+h9P/1IqGcAMbTJfMSO6hw4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eddy Wu , Oleg Nesterov , Linus Torvalds Subject: [PATCH 4.4 78/86] fork: fix copy_process(CLONE_PARENT) race with the exiting ->real_parent Date: Mon, 9 Nov 2020 13:55:25 +0100 Message-Id: <20201109125024.538785424@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201109125020.852643676@linuxfoundation.org> References: <20201109125020.852643676@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eddy Wu commit b4e00444cab4c3f3fec876dc0cccc8cbb0d1a948 upstream. current->group_leader->exit_signal may change during copy_process() if current->real_parent exits. Move the assignment inside tasklist_lock to avoid the race. Signed-off-by: Eddy Wu Acked-by: Oleg Nesterov Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- kernel/fork.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1539,14 +1539,9 @@ static struct task_struct *copy_process( /* ok, now we should be set up.. */ p->pid = pid_nr(pid); if (clone_flags & CLONE_THREAD) { - p->exit_signal = -1; p->group_leader = current->group_leader; p->tgid = current->tgid; } else { - if (clone_flags & CLONE_PARENT) - p->exit_signal = current->group_leader->exit_signal; - else - p->exit_signal = (clone_flags & CSIGNAL); p->group_leader = p; p->tgid = p->pid; } @@ -1591,9 +1586,14 @@ static struct task_struct *copy_process( if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { p->real_parent = current->real_parent; p->parent_exec_id = current->parent_exec_id; + if (clone_flags & CLONE_THREAD) + p->exit_signal = -1; + else + p->exit_signal = current->group_leader->exit_signal; } else { p->real_parent = current; p->parent_exec_id = current->self_exec_id; + p->exit_signal = (clone_flags & CSIGNAL); } spin_lock(¤t->sighand->siglock);