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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT 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 F2B67C43142 for ; Mon, 30 Jul 2018 18:54:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ABD2920870 for ; Mon, 30 Jul 2018 18:54:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ABD2920870 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731637AbeG3Uab (ORCPT ); Mon, 30 Jul 2018 16:30:31 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:47748 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730400AbeG3Uab (ORCPT ); Mon, 30 Jul 2018 16:30:31 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1C3D6E9017; Mon, 30 Jul 2018 18:54:11 +0000 (UTC) Received: from treble (ovpn-120-73.rdu2.redhat.com [10.10.120.73]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6C85A20389E0; Mon, 30 Jul 2018 18:54:10 +0000 (UTC) Date: Mon, 30 Jul 2018 13:54:08 -0500 From: Josh Poimboeuf To: Jeremy Cline Cc: Theodore Ts'o , Andreas Dilger , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2] ext4: mballoc: Fix spectre gadget in ext4_mb_regular_allocator Message-ID: <20180730185408.hl6omiitkqpac5d3@treble> References: <20180730180747.25200-1-jcline@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180730180747.25200-1-jcline@redhat.com> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Mon, 30 Jul 2018 18:54:11 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Mon, 30 Jul 2018 18:54:11 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'jpoimboe@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 30, 2018 at 06:07:47PM +0000, Jeremy Cline wrote: > 'ac->ac_g_ex.fe_len' is a user-controlled value which is used in the > derivation of 'ac->ac_2order'. 'ac->ac_2order', in turn, is used to > index arrays which makes it a potential spectre gadget. Fix this by > sanitizing the value assigned to 'ac->ac2_order'. This covers the > following accesses found with the help of smatch: > > * fs/ext4/mballoc.c:1896 ext4_mb_simple_scan_group() warn: potential > spectre issue 'grp->bb_counters' [w] (local cap) > > * fs/ext4/mballoc.c:445 mb_find_buddy() warn: potential spectre issue > 'EXT4_SB(e4b->bd_sb)->s_mb_offsets' [r] (local cap) > > * fs/ext4/mballoc.c:446 mb_find_buddy() warn: potential spectre issue > 'EXT4_SB(e4b->bd_sb)->s_mb_maxs' [r] (local cap) > > Cc: Josh Poimboeuf > Cc: stable@vger.kernel.org > Suggested-by: Josh Poimboeuf > Signed-off-by: Jeremy Cline Reviewed-by: Josh Poimboeuf -- Josh