From patchwork Mon Nov 9 12:55:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 322768 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 0E72CC388F7 for ; Mon, 9 Nov 2020 13:10:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B992320663 for ; Mon, 9 Nov 2020 13:10:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604927433; bh=v2/IidOou76DgT2D9TlB3R5aId4pHa4kqdlHwriWQYg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=cVbwtmKc2nf64wy98mIyW9BbBMtodEmE0iw52RtG53nCTZAwDPLtImUjUzwGNueJI wGqSrUGjv1BWH6YwpL0urjupk7UfJB88tNg/l4CwwAEirVHSt009EKPXII8p6UvVIz 9zUFs5kMe70F9KttPfIAz/1hmklbtJ++9Bixmzak= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732092AbgKINKc (ORCPT ); Mon, 9 Nov 2020 08:10:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:35790 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732084AbgKINKb (ORCPT ); Mon, 9 Nov 2020 08:10:31 -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 443092076E; Mon, 9 Nov 2020 13:10:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604927429; bh=v2/IidOou76DgT2D9TlB3R5aId4pHa4kqdlHwriWQYg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gjL/3lTV7XDe7HY+Z7MgnHo51ts/xFSjK7eIij53cMq0m9+6OpJHNvxHIP8sgY8AT wCYC1V9BF1ubBEOF9gMYc2VQnLPyktJ7n78Vl5DkCT7qDBLIf6PLX4Lsyywflr5j9/ cTFOsfFLpPQjnsjFI9OaZ7htf0BrW9mnoNNBW4So= 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 4.19 56/71] fork: fix copy_process(CLONE_PARENT) race with the exiting ->real_parent Date: Mon, 9 Nov 2020 13:55:50 +0100 Message-Id: <20201109125022.535216218@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201109125019.906191744@linuxfoundation.org> References: <20201109125019.906191744@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 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 @@ -1965,14 +1965,9 @@ static __latent_entropy struct task_stru /* 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; } @@ -2017,9 +2012,14 @@ static __latent_entropy struct task_stru 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); } klp_copy_process(p);