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,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 94363C3A5A8 for ; Wed, 4 Sep 2019 16:03:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6B3C72087E for ; Wed, 4 Sep 2019 16:03:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567613002; bh=yLnWCBzURFYaphma3SALcWe00G9AD5Jynb2Nanj3EW4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zavFAYnZD5abLRMrar64T7v/jdDUNMTgRA8hZGg+GqM0NU9FwQ1QN39hecC0lED6R yFjrHuFHGMrpdsyXcxN9QxgqIwbFt6/BuQSMXr93YibxeYn+StHqF/8/m0jTFK3xp/ /Bu2l6kf6ruwBvDHvrzaqGp2WCA07eIhNX2PydCk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732882AbfIDQDS (ORCPT ); Wed, 4 Sep 2019 12:03:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:39642 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732901AbfIDQDO (ORCPT ); Wed, 4 Sep 2019 12:03:14 -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 6561022CF5; Wed, 4 Sep 2019 16:03:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567612993; bh=yLnWCBzURFYaphma3SALcWe00G9AD5Jynb2Nanj3EW4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jIlRVpVnzyJklvGyQj1ZUI5TaOx7dDGd+6IscsR04rdk4AGs2Xe+8vFU773JPSV09 ZKpl/wxTze2IKrymsieIqlleyNEeS1FJV/qCCetnuLN/UQ0unk+aXLfIkp4ZiJfZI8 XxRGR1zBVRA1ouE7Y8JJ+rzyIbP0r2teqv5TErxc= 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 4.4 07/20] ARM: 8874/1: mm: only adjust sections of valid mm structures Date: Wed, 4 Sep 2019 12:02:50 -0400 Message-Id: <20190904160303.5062-7-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190904160303.5062-1-sashal@kernel.org> References: <20190904160303.5062-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 a9f6705aea238..731b7e64715b9 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -691,7 +691,8 @@ 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