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=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 94E13C282CB for ; Mon, 4 Feb 2019 22:10:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 690C82082E for ; Mon, 4 Feb 2019 22:10:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726584AbfBDWJz convert rfc822-to-8bit (ORCPT ); Mon, 4 Feb 2019 17:09:55 -0500 Received: from mga14.intel.com ([192.55.52.115]:15726 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725874AbfBDWJz (ORCPT ); Mon, 4 Feb 2019 17:09:55 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 04 Feb 2019 14:09:55 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,560,1539673200"; d="scan'208";a="121975330" Received: from fmsmsx104.amr.corp.intel.com ([10.18.124.202]) by fmsmga008.fm.intel.com with ESMTP; 04 Feb 2019 14:09:54 -0800 Received: from fmsmsx114.amr.corp.intel.com (10.18.116.8) by fmsmsx104.amr.corp.intel.com (10.18.124.202) with Microsoft SMTP Server (TLS) id 14.3.408.0; Mon, 4 Feb 2019 14:09:54 -0800 Received: from hasmsx111.ger.corp.intel.com (10.184.198.39) by FMSMSX114.amr.corp.intel.com (10.18.116.8) with Microsoft SMTP Server (TLS) id 14.3.408.0; Mon, 4 Feb 2019 14:09:54 -0800 Received: from hasmsx108.ger.corp.intel.com ([169.254.9.55]) by HASMSX111.ger.corp.intel.com ([169.254.5.16]) with mapi id 14.03.0415.000; Tue, 5 Feb 2019 00:09:51 +0200 From: "Winkler, Tomas" To: Jarkko Sakkinen , "linux-integrity@vger.kernel.org" CC: "linux-kernel@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "stable@vger.kernel.org" , James Morris , Jerry Snitselaar Subject: RE: [PATCH v2] tpm/tpm_crb: Avoid unaligned reads in crb_recv() Thread-Topic: [PATCH v2] tpm/tpm_crb: Avoid unaligned reads in crb_recv() Thread-Index: AQHUvJHo5McHpPxFx06wzUIdLLf3u6XQMmYw Date: Mon, 4 Feb 2019 22:09:51 +0000 Message-ID: <5B8DA87D05A7694D9FA63FD143655C1B9DA901F7@hasmsx108.ger.corp.intel.com> References: <20190204135943.15756-1-jarkko.sakkinen@linux.intel.com> In-Reply-To: <20190204135943.15756-1-jarkko.sakkinen@linux.intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-product: dlpe-windows dlp-version: 11.0.400.15 dlp-reaction: no-action x-originating-ip: [10.12.126.72] 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: James Morris > Cc: Tomas Winkler > Cc: Jerry Snitselaar > Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface") > Signed-off-by: Jarkko Sakkinen > Reviewed-by: Jerry Snitselaar After fixing the typos you can add my ack. Thanks Tomas > --- > v2: > * There was a trailing double colon in the end of the short summary. > * Check requested and expected length against TPM_HEADER_SIZE. > * Add some explanatory comments to crb_recv(). > drivers/char/tpm/tpm_crb.c | 22 ++++++++++++++++------ > 1 file changed, 16 insertions(+), 6 deletions(-) > > diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c index > 36952ef98f90..c084e61299aa 100644 > --- a/drivers/char/tpm/tpm_crb.c > +++ b/drivers/char/tpm/tpm_crb.c > @@ -287,19 +287,29 @@ static int crb_recv(struct tpm_chip *chip, u8 *buf, > size_t count) > struct crb_priv *priv = dev_get_drvdata(&chip->dev); > unsigned int expected; > > - /* sanity check */ > - if (count < 6) > + /* A sanity check that the upper layer wants to get at least the header > + * as that is the minimum size for any TPM response. > + */ > + if (count < TPM_HEADER_SIZE) > return -EIO; > > + /* If this bit is set, according to the spec, the TPM is in unrecovable ^^^ typo ^^^^ > + * condition. > + */ > if (ioread32(&priv->regs_t->ctrl_sts) & CRB_CTRL_STS_ERROR) > return -EIO; > > - memcpy_fromio(buf, priv->rsp, 6); > - expected = be32_to_cpup((__be32 *) &buf[2]); > - if (expected > count || expected < 6) > + /* Read 8 bytes (not just 6 bytes, which would cover ^^^ tag and^^^ the response > length > + * field ^^^s^^^) in order to make sure that the reminding memory accesses ^^^ remaining^^^ > will > + * be aligned. > + */ > + memcpy_fromio(buf, priv->rsp, 8); > + > + expected = be32_to_cpup((__be32 *)&buf[2]); > + if (expected > count || expected < TPM_HEADER_SIZE) > return -EIO; > > - memcpy_fromio(&buf[6], &priv->rsp[6], expected - 6); > + memcpy_fromio(&buf[8], &priv->rsp[8], expected - 8); > > return expected; > } > -- > 2.19.1