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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 584FAC3A5AA for ; Wed, 4 Sep 2019 16:18:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2CBF02053B for ; Wed, 4 Sep 2019 16:18:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567613935; bh=ep+37ZmQaFe9khzB1Ublxq7aT04QtrRwFlS7AmDIN7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MS8pctpx8hMWYl87qCNVJ7tmnC+YJ3s39ZsYCN763qeS69z/7Sba+QgXwn8Ln2rKG SYlmYS6uM7pHcMcDpeh1DHCZZIRjcy9/wULjtUcTm/gGQPzA0v0s3e6b2FNOD6AvsB mtylXbD2Egm9scJjgGDfihrFc8bFW+tX0wB4vISk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731971AbfIDP6h (ORCPT ); Wed, 4 Sep 2019 11:58:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:60876 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732028AbfIDP6f (ORCPT ); Wed, 4 Sep 2019 11:58:35 -0400 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 330D523402; Wed, 4 Sep 2019 15:58:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567612714; bh=ep+37ZmQaFe9khzB1Ublxq7aT04QtrRwFlS7AmDIN7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Eu1ZeAPEyrvoWQe6C+Yp4gxaHkvM5xrP0W2U2ElcUBkwAgyY7ZEoidXgClx8MTv5a jO3+sRKDYx4+zIPLmibXSlJSNEYHiKj6Hq0aeUeStkOpJ6wHAUb5z7VQG+DwZAklRh xy07gywUS3TeS2Gt//O/tnkbXNMwgfAoIX4wmJeA= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Doug Berger , Laura Abbott , Mike Rapoport , Andrew Morton , Florian Fainelli , Rob Herring , "Steven Rostedt (VMware)" , Peng Fan , Geert Uytterhoeven , Russell King , Sasha Levin Subject: [PATCH AUTOSEL 5.2 37/94] ARM: 8874/1: mm: only adjust sections of valid mm structures Date: Wed, 4 Sep 2019 11:56:42 -0400 Message-Id: <20190904155739.2816-37-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190904155739.2816-1-sashal@kernel.org> References: <20190904155739.2816-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Doug Berger [ Upstream commit c51bc12d06b3a5494fbfcbd788a8e307932a06e9 ] A timing hazard exists when an early fork/exec thread begins exiting and sets its mm pointer to NULL while a separate core tries to update the section information. This commit ensures that the mm pointer is not NULL before setting its section parameters. The arguments provided by commit 11ce4b33aedc ("ARM: 8672/1: mm: remove tasklist locking from update_sections_early()") are equally valid for not requiring grabbing the task_lock around this check. Fixes: 08925c2f124f ("ARM: 8464/1: Update all mm structures with section adjustments") Signed-off-by: Doug Berger Acked-by: Laura Abbott Cc: Mike Rapoport Cc: Andrew Morton Cc: Florian Fainelli Cc: Rob Herring Cc: "Steven Rostedt (VMware)" Cc: Peng Fan Cc: Geert Uytterhoeven Signed-off-by: Russell King Signed-off-by: Sasha Levin --- arch/arm/mm/init.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index 749a5a6f61433..8e793cddac661 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -613,7 +613,8 @@ static void update_sections_early(struct section_perm perms[], int n) if (t->flags & PF_KTHREAD) continue; for_each_thread(t, s) - set_section_perms(perms, n, true, s->mm); + if (s->mm) + set_section_perms(perms, n, true, s->mm); } set_section_perms(perms, n, true, current->active_mm); set_section_perms(perms, n, true, &init_mm); -- 2.20.1