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=-6.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS 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 80720C43387 for ; Thu, 3 Jan 2019 15:24:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 49F882070D for ; Thu, 3 Jan 2019 15:24:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="nRGZSlim" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730789AbfACPYA (ORCPT ); Thu, 3 Jan 2019 10:24:00 -0500 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:53104 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728208AbfACPYA (ORCPT ); Thu, 3 Jan 2019 10:24:00 -0500 Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 384C38EE268; Thu, 3 Jan 2019 07:24:00 -0800 (PST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id aaUzFgb53Y9n; Thu, 3 Jan 2019 07:24:00 -0800 (PST) Received: from [153.66.254.194] (unknown [50.35.68.20]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id B31278EE0A4; Thu, 3 Jan 2019 07:23:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1546529039; bh=z4MmgaS6a6IiFfs5BXth4/Q45jA9kTUL5VvdxyP6w0s=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=nRGZSlimTiYbJlVdtjujGt1fjUSCO3Hl/8lGUAh7BJCJP4siXK8LrSw8TEB83pFmB imGrVnS4jgNspZotGbFDeqkbo7ItyZON94JEgM7EIX6XJLv5NAIMuq1g2/ZDp+Io7i DtQsOXQpv6O1Sz3WM7zL8bABUKgM/aFlEurL7jtI= Message-ID: <1546529038.2824.6.camel@HansenPartnership.com> Subject: Re: [PATCH] tpm: fix incorrect success returns from tpm_try_transmit() From: James Bottomley To: Jarkko Sakkinen Cc: Tomas Winkler , linux-integrity@vger.kernel.org Date: Thu, 03 Jan 2019 07:23:58 -0800 In-Reply-To: <20190103125904.GA10491@linux.intel.com> References: <1546280851.3079.2.camel@HansenPartnership.com> <20190103125904.GA10491@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Thu, 2019-01-03 at 14:59 +0200, Jarkko Sakkinen wrote: > On Mon, Dec 31, 2018 at 10:27:31AM -0800, James Bottomley wrote: > > Ever since 627448e85c766 "tpm: separate cmd_ready/go_idle from > > runtime_pm" we have been returning success from tpm_try_transmit() > > even if an error occurred. The reason is that the introduction of > > rc > > = tpm_go_idle() at the end of processing overwrites the value of rc > > if > > it contains an error code (mostly with success). Fix this by > > writing > > the return to a new variable rc1 instead. > > > > Fixes: 627448e85c766 "tpm: separate cmd_ready/go_idle from > > runtime_pm" > > Cc: stable@vger.kernel.org > > Signed-off-by: James Bottomley > om> > > > > --- > > > > Note: the goto out looks fishy as well. The only go_idle > > implementor > > is tpm_crb and that can return a timeout as -ETIME, so it looks > > like it > > would then loop forever > > > > diff --git a/drivers/char/tpm/tpm-interface.c > > b/drivers/char/tpm/tpm-interface.c > > index 129f640424b7..ac7ebab6140c 100644 > > --- a/drivers/char/tpm/tpm-interface.c > > +++ b/drivers/char/tpm/tpm-interface.c > > @@ -432,7 +432,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip > > *chip, > > unsigned int flags) > > { > > struct tpm_output_header *header = (void *)buf; > > - int rc; > > + int rc, rc1; > > ssize_t len = 0; > > u32 count, ordinal; > > unsigned long stop; > > @@ -547,8 +547,8 @@ static ssize_t tpm_try_transmit(struct tpm_chip > > *chip, > > dev_err(&chip->dev, "tpm2_commit_space: error > > %d\n", rc); > > > > out: > > - rc = tpm_go_idle(chip, flags); > > - if (rc) > > + rc1 = tpm_go_idle(chip, flags); > > + if (rc1) > > goto out; > > > > if (need_locality) > > Thanks James and sorry for latency (holiday season). Just a small > suggestion. I would just: > > if (tpm_go_idle(chip, flags)) > goto out; > > What do you think? That it doesn't solve the loop forever with no warning problem. If anything, I think the correct thing is probably rc1 = tpm_go_idle(chip, flags); if (rc1) dev_err(&chip->dev, "go idle failed with %d\n", rc1); so we log the problem and move on. If it is a timeout, it will likely show up on the next TPM operation. Since this is the only caller of tpm_go_idle(), I think all looping should be done inside that function, but we should probably wait for Tomas to comment since he wrote it. James