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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 0E87EC10F11 for ; Wed, 24 Apr 2019 17:38:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D46CD218B0 for ; Wed, 24 Apr 2019 17:38:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556127488; bh=p+jBVZs35rk9TKVCeijqSwaj9ywYFKMuGFHdlkuTxNQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=N4qlxp/dyBs88uiJRACOXeFZhPp/iHmLLYNvqBa75mTXItk64O8ysbxFFsxiv2zky ann3RjGL9dhh0wYEWLfUl0EzSQqhh79uvdonN9nLxzOFXhE+idaAp0fkgBCepiVv6J jiVboiwCIVGmXxaGGeuO6qIsbvpGIwMUQFCpfD0A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392353AbfDXRiH (ORCPT ); Wed, 24 Apr 2019 13:38:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:37220 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392336AbfDXRiF (ORCPT ); Wed, 24 Apr 2019 13:38:05 -0400 Received: from localhost (62-193-50-229.as16211.net [62.193.50.229]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0D6AB218B0; Wed, 24 Apr 2019 17:38:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556127484; bh=p+jBVZs35rk9TKVCeijqSwaj9ywYFKMuGFHdlkuTxNQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rrkFkycGvXoxBVuYPn8sb/PhwtReOqWF1rbhbb7IbiOezLmpXAleIWFPpuo01sGlQ asIzJHyeXWCnqIyBdfQFt/+gwFe5WtIWjavNFEYh8Tne6ZzYgshHmSWjKnHG5FKGxA hzmneOdX6FoPbkDhYSPjItckD3qcy1yiaiEZc5y8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Mantas=20Mikul=C4=97nas?= , Tadeusz Struk , Jarkko Sakkinen , James Morris , Sasha Levin Subject: [PATCH 5.0 108/115] tpm: fix an invalid condition in tpm_common_poll Date: Wed, 24 Apr 2019 19:10:44 +0200 Message-Id: <20190424170931.001860087@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190424170924.797924502@linuxfoundation.org> References: <20190424170924.797924502@linuxfoundation.org> User-Agent: quilt/0.66 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 [ Upstream commit 7110629263469b4664d00b38ef80a656eddf3637 ] 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 Tested-by: Mantas Mikulėnas Signed-off-by: Tadeusz Struk Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen Signed-off-by: James Morris Signed-off-by: Sasha Levin --- drivers/char/tpm/tpm-dev-common.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c index 5eecad233ea1..744b0237300a 100644 --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -203,12 +203,19 @@ __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) + /* + * The response_length indicates if there is still response + * (or part of it) to be consumed. Partial reads decrease it + * by the number of bytes read, and write resets it the zero. + */ + if (priv->response_length) mask = EPOLLIN | EPOLLRDNORM; else mask = EPOLLOUT | EPOLLWRNORM; + mutex_unlock(&priv->buffer_mutex); return mask; } -- 2.19.1