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 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 948A0C10F03 for ; Tue, 19 Mar 2019 20:31:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 644462082F for ; Tue, 19 Mar 2019 20:31:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727384AbfCSUbg (ORCPT ); Tue, 19 Mar 2019 16:31:36 -0400 Received: from mga18.intel.com ([134.134.136.126]:19688 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726740AbfCSUbf (ORCPT ); Tue, 19 Mar 2019 16:31:35 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Mar 2019 13:31:34 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,245,1549958400"; d="scan'208";a="126830422" Received: from tstruk-mobl1.jf.intel.com ([10.7.196.61]) by orsmga008.jf.intel.com with ESMTP; 19 Mar 2019 13:31:34 -0700 Subject: [PATCH v2] tpm: fix an invalid condition in tpm_common_poll From: Tadeusz Struk To: jarkko.sakkinen@linux.intel.com Cc: grawity@gmail.com, James.Bottomley@HansenPartnership.com, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, tadeusz.struk@intel.com Date: Tue, 19 Mar 2019 13:31:34 -0700 Message-ID: <155302749437.13955.651380639754310898.stgit@tstruk-mobl1.jf.intel.com> User-Agent: StGit/unknown-version MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The poll condition should only check response_length, because reads should only be issued if there is data to read. The response_read flag only prevents double writes. The problem was that the write set the response_read to false, enqued a tpm job, and returned. Then application called poll which checked the response_read flag and returned EPOLLIN. Then the application called read, but got nothing. After all that the async_work kicked in. Added also mutex_lock around the poll check to prevent other possible race conditions. Fixes: 9488585b21bef0df12 ("tpm: add support for partial reads") Reported-by: Mantas Mikulėnas Signed-off-by: Tadeusz Struk --- drivers/char/tpm/tpm-dev-common.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c index 5eecad233ea1..7312d3214381 100644 --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -203,12 +203,14 @@ __poll_t tpm_common_poll(struct file *file, poll_table *wait) __poll_t mask = 0; poll_wait(file, &priv->async_wait, wait); + mutex_lock(&priv->buffer_mutex); - if (!priv->response_read || priv->response_length) + if (priv->response_length) mask = EPOLLIN | EPOLLRDNORM; else mask = EPOLLOUT | EPOLLWRNORM; + mutex_unlock(&priv->buffer_mutex); return mask; }