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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 03BE5C49ED7 for ; Thu, 19 Sep 2019 22:20:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C8E7A21924 for ; Thu, 19 Sep 2019 22:20:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568931619; bh=U7yRzAYMW30TIjYy8RlK1FZ5pZc4dDGGUPsgsBmMOss=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zRIdaBi8g6Rg+Y0R96308KBWYUF4Pt4yIJjdRnEWlr12GjlYKWxIXHG7W3dDdGRQY hCHLvEsSTU+iF2imocyNWFVuU+k3/sv7eWDI3eZbEVbcUKxSZAMek97YtfMQZIh/Vd XApCZ/Y5cADyjLRywmkaxRuezOlMD2Ccd50VLyzE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405678AbfISWUT (ORCPT ); Thu, 19 Sep 2019 18:20:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:34188 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392769AbfISWUR (ORCPT ); Thu, 19 Sep 2019 18:20:17 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 3AC1A21920; Thu, 19 Sep 2019 22:20:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568931616; bh=U7yRzAYMW30TIjYy8RlK1FZ5pZc4dDGGUPsgsBmMOss=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ub/z6k+wOCgbnST63uMJjCVdIF9vLfH8cHn3bSic4jgDBAhTka1mjXTmSZSNbXqk4 XAv4BqGYBM+5r5qeVvtw8uNvHaQzfbEy0gD/g+IA382o6bXqtZrHTQuvuy24eJ0ld6 cA0s23JIxuKi8Ll+sVLb6I/iMQY48mbL5j3zoMnI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, 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 4.9 52/74] ARM: 8874/1: mm: only adjust sections of valid mm structures Date: Fri, 20 Sep 2019 00:04:05 +0200 Message-Id: <20190919214809.928390624@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190919214800.519074117@linuxfoundation.org> References: <20190919214800.519074117@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 1565d6b671636..4fb1474141a61 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -698,7 +698,8 @@ 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); } read_unlock(&tasklist_lock); set_section_perms(perms, n, true, current->active_mm); -- 2.20.1