From patchwork Fri Jan 11 08:59:32 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia Zhang X-Patchwork-Id: 10757531 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6D8196C5 for ; Fri, 11 Jan 2019 09:00:21 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5C98D26E3D for ; Fri, 11 Jan 2019 09:00:21 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5093C28DEC; Fri, 11 Jan 2019 09:00:21 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DD0F426E3D for ; Fri, 11 Jan 2019 09:00:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727900AbfAKJAU (ORCPT ); Fri, 11 Jan 2019 04:00:20 -0500 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:55295 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725779AbfAKJAU (ORCPT ); Fri, 11 Jan 2019 04:00:20 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04420;MF=zhang.jia@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0TI.JvuE_1547197175; Received: from localhost(mailfrom:zhang.jia@linux.alibaba.com fp:SMTPD_---0TI.JvuE_1547197175) by smtp.aliyun-inc.com(127.0.0.1); Fri, 11 Jan 2019 16:59:35 +0800 From: Jia Zhang To: jarkko.sakkinen@linux.intel.com, peterhuewe@gmx.de, jgg@ziepe.ca, tweek@google.com Cc: linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, zhang.jia@linux.alibaba.com Subject: [PATCH 1/2] tpm/eventlog/tpm1: Simplify walking over *pos measurements Date: Fri, 11 Jan 2019 16:59:32 +0800 Message-Id: <1547197173-52826-2-git-send-email-zhang.jia@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1547197173-52826-1-git-send-email-zhang.jia@linux.alibaba.com> References: <1547197173-52826-1-git-send-email-zhang.jia@linux.alibaba.com> Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The responsibility of tpm1_bios_measurements_start() is to walk over the first *pos measurements, ensuring the skipped and to-be-read measurements are not out-of-boundary. Current logic is complicated a bit. Just employ a do-while loop with necessary sanity check, and then get the goal. Signed-off-by: Jia Zhang --- drivers/char/tpm/eventlog/tpm1.c | 37 ++++++++++++++----------------------- 1 file changed, 14 insertions(+), 23 deletions(-) diff --git a/drivers/char/tpm/eventlog/tpm1.c b/drivers/char/tpm/eventlog/tpm1.c index 58c8478..4cf8303 100644 --- a/drivers/char/tpm/eventlog/tpm1.c +++ b/drivers/char/tpm/eventlog/tpm1.c @@ -74,7 +74,7 @@ /* returns pointer to start of pos. entry of tcg log */ static void *tpm1_bios_measurements_start(struct seq_file *m, loff_t *pos) { - loff_t i; + loff_t i = 0; struct tpm_chip *chip = m->private; struct tpm_bios_log *log = &chip->log; void *addr = log->bios_event_log; @@ -83,38 +83,29 @@ static void *tpm1_bios_measurements_start(struct seq_file *m, loff_t *pos) u32 converted_event_size; u32 converted_event_type; - /* read over *pos measurements */ - for (i = 0; i < *pos; i++) { + do { event = addr; + /* check if current entry is valid */ + if (addr + sizeof(struct tcpa_event) >= limit) + return NULL; + converted_event_size = do_endian_conversion(event->event_size); converted_event_type = do_endian_conversion(event->event_type); - if ((addr + sizeof(struct tcpa_event)) < limit) { - if ((converted_event_type == 0) && - (converted_event_size == 0)) - return NULL; - addr += (sizeof(struct tcpa_event) + - converted_event_size); - } - } - - /* now check if current entry is valid */ - if ((addr + sizeof(struct tcpa_event)) >= limit) - return NULL; - - event = addr; + if (((converted_event_type == 0) && (converted_event_size == 0)) + || ((addr + sizeof(struct tcpa_event) + converted_event_size) + >= limit)) + return NULL; - converted_event_size = do_endian_conversion(event->event_size); - converted_event_type = do_endian_conversion(event->event_type); + if (i++ == *pos) + break; - if (((converted_event_type == 0) && (converted_event_size == 0)) - || ((addr + sizeof(struct tcpa_event) + converted_event_size) - >= limit)) - return NULL; + addr += (sizeof(struct tcpa_event) + converted_event_size); + } while (1); return addr; }