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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,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 96100C5517A for ; Tue, 10 Nov 2020 03:55:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B0B621534 for ; Tue, 10 Nov 2020 03:55:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="03EqFjSX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731346AbgKJDzs (ORCPT ); Mon, 9 Nov 2020 22:55:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:57194 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733238AbgKJDzk (ORCPT ); Mon, 9 Nov 2020 22:55:40 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id F0EC120721; Tue, 10 Nov 2020 03:55:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604980539; bh=Uj+mF2sGtL3UqV+CXThkW1T2xj7DYSonhxRtvtwdmKo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=03EqFjSX+tQCf0fOx3iCEkmGtYl/nwqfe6C7tvHpLIEPbllv8+ijwNXE7sXhMYY+v WiSNh9EusK6BcYH9XVnfpnMp8/HPkU7GzLvs2uhAxQvMrcbx/NpYHnxH+ieesi6Jq2 pem0snZQDK2cJu4yeU2B0+djpIh+4PPL5DHkbS0Q= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eddy Wu , Eddy Wu , Oleg Nesterov , Linus Torvalds , Sasha Levin Subject: [PATCH AUTOSEL 5.4 42/42] fork: fix copy_process(CLONE_PARENT) race with the exiting ->real_parent Date: Mon, 9 Nov 2020 22:54:40 -0500 Message-Id: <20201110035440.424258-42-sashal@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20201110035440.424258-1-sashal@kernel.org> References: <20201110035440.424258-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eddy Wu [ Upstream commit b4e00444cab4c3f3fec876dc0cccc8cbb0d1a948 ] 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: Sasha Levin --- kernel/fork.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index e3d5963d8c6f5..419fff8eb9e55 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2100,14 +2100,9 @@ static __latent_entropy 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 = args->exit_signal; p->group_leader = p; p->tgid = p->pid; } @@ -2152,9 +2147,14 @@ static __latent_entropy 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 = args->exit_signal; } klp_copy_process(p); -- 2.27.0