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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 45EDAC282D8 for ; Fri, 1 Feb 2019 19:20:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 20BAC218AF for ; Fri, 1 Feb 2019 19:20:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727722AbfBATUu convert rfc822-to-8bit (ORCPT ); Fri, 1 Feb 2019 14:20:50 -0500 Received: from mga17.intel.com ([192.55.52.151]:25175 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbfBATUu (ORCPT ); Fri, 1 Feb 2019 14:20:50 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 01 Feb 2019 11:20:49 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,549,1539673200"; d="scan'208";a="114582532" Received: from fmsmsx107.amr.corp.intel.com ([10.18.124.205]) by orsmga008.jf.intel.com with ESMTP; 01 Feb 2019 11:20:49 -0800 Received: from fmsmsx154.amr.corp.intel.com (10.18.116.70) by fmsmsx107.amr.corp.intel.com (10.18.124.205) with Microsoft SMTP Server (TLS) id 14.3.408.0; Fri, 1 Feb 2019 11:20:49 -0800 Received: from HASMSX110.ger.corp.intel.com (10.184.198.28) by FMSMSX154.amr.corp.intel.com (10.18.116.70) with Microsoft SMTP Server (TLS) id 14.3.408.0; Fri, 1 Feb 2019 11:20:46 -0800 Received: from hasmsx108.ger.corp.intel.com ([169.254.9.55]) by HASMSX110.ger.corp.intel.com ([169.254.6.213]) with mapi id 14.03.0415.000; Fri, 1 Feb 2019 21:20:43 +0200 From: "Winkler, Tomas" To: Jarkko Sakkinen , "linux-kernel@vger.kernel.org" CC: "linux-integrity@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "stable@vger.kernel.org" , Linus Torvalds , James Morris , Jerry Snitselaar Subject: RE: [PATCH] tpm/tpm_crb: Avoid unaligned reads in crb_recv(): Thread-Topic: [PATCH] tpm/tpm_crb: Avoid unaligned reads in crb_recv(): Thread-Index: AQHUuiILqL/DhC1Ugk6fMR5NQMo3vKXLTG+Q Date: Fri, 1 Feb 2019 19:20:42 +0000 Message-ID: <5B8DA87D05A7694D9FA63FD143655C1B9DA8E215@hasmsx108.ger.corp.intel.com> References: <20190201111949.14881-1-jarkko.sakkinen@linux.intel.com> In-Reply-To: <20190201111949.14881-1-jarkko.sakkinen@linux.intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ctpclassification: CTP_NT x-titus-metadata-40: eyJDYXRlZ29yeUxhYmVscyI6IiIsIk1ldGFkYXRhIjp7Im5zIjoiaHR0cDpcL1wvd3d3LnRpdHVzLmNvbVwvbnNcL0ludGVsMyIsImlkIjoiMDcxMjQyNTktMmZkNC00MzYwLWFkNzgtZjNjYTFjM2U3ZTgzIiwicHJvcHMiOlt7Im4iOiJDVFBDbGFzc2lmaWNhdGlvbiIsInZhbHMiOlt7InZhbHVlIjoiQ1RQX05UIn1dfV19LCJTdWJqZWN0TGFiZWxzIjpbXSwiVE1DVmVyc2lvbiI6IjE3LjEwLjE4MDQuNDkiLCJUcnVzdGVkTGFiZWxIYXNoIjoieXhjWjdrUFJaSndlMlNzNXVKbUtNMUhNSXdhUVFZdm0yd1p4ZTFtMkFwdWVzNlhXblZkXC8rTFB1QkpEeVpka1AifQ== dlp-product: dlpe-windows dlp-version: 11.0.400.15 dlp-reaction: no-action x-originating-ip: [10.254.159.176] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org > > The current approach to read first 6 bytes from the response and then tail of > the response, can cause the 2nd memcpy_fromio() to do an unaligned read > (e.g. read 32-bit word from address aligned to a 16-bits), depending on how > memcpy_fromio() is implemented. If this happens, the read will fail and the > memory controller will fill the read with 1's. > > This was triggered by 170d13ca3a2f, which should be probably refined to check > and react to the address alignment. Before that commit, on x86 > memcpy_fromio() turned out to be memcpy(). By a luck GCC has done the right > thing (from tpm_crb's perspective) for us so far, but we should not rely on that. > Thus, it makes sense to fix this also in tpm_crb, not least because the fix can be > then backported to stable kernels and make them more robust when compiled > in differing environments. > > Cc: stable@vger.kernel.org > Cc: Linus Torvalds > Cc: James Morris > Cc: Tomas Winkler > Cc: Jerry Snitselaar > Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface") > Signed-off-by: Jarkko Sakkinen > --- > drivers/char/tpm/tpm_crb.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c index > 36952ef98f90..7f47e43aa9f1 100644 > --- a/drivers/char/tpm/tpm_crb.c > +++ b/drivers/char/tpm/tpm_crb.c > @@ -288,18 +288,18 @@ static int crb_recv(struct tpm_chip *chip, u8 *buf, > size_t count) > unsigned int expected; > > /* sanity check */ > - if (count < 6) > + if (count < 8) > return -EIO; Why don't you already enforce reading at least the whole TPM header 10bytes, we are reading the whole buffer at one call anyway. Who every is asking for 8 bytes from the protocol level, is doing something wrong. > if (ioread32(&priv->regs_t->ctrl_sts) & CRB_CTRL_STS_ERROR) > return -EIO; > > - memcpy_fromio(buf, priv->rsp, 6); > + memcpy_fromio(buf, priv->rsp, 8); Maybe a short comment will spare someone looking into git history > expected = be32_to_cpup((__be32 *) &buf[2]); > - if (expected > count || expected < 6) > + if (expected > count || expected < 8) Expected should be at least tpm header, right? > return -EIO; > > - memcpy_fromio(&buf[6], &priv->rsp[6], expected - 6); > + memcpy_fromio(&buf[8], &priv->rsp[8], expected - 8); > > return expected; > } Otherwise ready the first 8 bytes looks good. Thanks Tomas