From patchwork Tue Sep 29 10:59:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 263309 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=-13.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, 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 D22F0C4741F for ; Tue, 29 Sep 2020 11:33:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9E0BC23B1A for ; Tue, 29 Sep 2020 11:33:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601379218; bh=2UQ9DFaxS2qeBIdJST9eYG/tl8Ou/LtUg3wFI3kjC04=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=nCDX6HuPI8A8SFg2PTFExCKC9BBLAoQPg0c/ek5zHr3q+N76Am6o34SKGo3NJa9d0 a9z3cffPWRp08oDI+bIpFbTht3phv+iAdUYZXmbiza/6lt9y4rLJh6UHkUmi8PGDOO 312Jxmr9KPJtYHP9SEA2Uf6f71QhLc7u3vj/FYEU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729073AbgI2Ldg (ORCPT ); Tue, 29 Sep 2020 07:33:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:50012 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729604AbgI2Ld1 (ORCPT ); Tue, 29 Sep 2020 07:33:27 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 B4B3223B99; Tue, 29 Sep 2020 11:26:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601378812; bh=2UQ9DFaxS2qeBIdJST9eYG/tl8Ou/LtUg3wFI3kjC04=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=p4KGSPV4V0briqR1i9iF0gZjkvc45jHtiB7/iPdL7sGIjxi+R1JdvzLgR7jq++vH4 ooR25f/ykC1XtIZ5N3wjSN8diOYp5sGD7d1nVWFHI1nbDOLsV5FLyM4eFrtA6Wegy1 +hq/KAt67TnIktHa+fhdL2jhB7m5d9n4wRSnZgys= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Madhuparna Bhowmik , Sasha Levin Subject: [PATCH 4.19 148/245] drivers: char: tlclk.c: Avoid data race between init and interrupt handler Date: Tue, 29 Sep 2020 12:59:59 +0200 Message-Id: <20200929105954.189934904@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200929105946.978650816@linuxfoundation.org> References: <20200929105946.978650816@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Madhuparna Bhowmik [ Upstream commit 44b8fb6eaa7c3fb770bf1e37619cdb3902cca1fc ] After registering character device the file operation callbacks can be called. The open callback registers interrupt handler. Therefore interrupt handler can execute in parallel with rest of the init function. To avoid such data race initialize telclk_interrupt variable and struct alarm_events before registering character device. Found by Linux Driver Verification project (linuxtesting.org). Signed-off-by: Madhuparna Bhowmik Link: https://lore.kernel.org/r/20200417153451.1551-1-madhuparnabhowmik10@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/char/tlclk.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/drivers/char/tlclk.c b/drivers/char/tlclk.c index 8eeb4190207d1..dce22b7fc5449 100644 --- a/drivers/char/tlclk.c +++ b/drivers/char/tlclk.c @@ -776,17 +776,21 @@ static int __init tlclk_init(void) { int ret; + telclk_interrupt = (inb(TLCLK_REG7) & 0x0f); + + alarm_events = kzalloc( sizeof(struct tlclk_alarms), GFP_KERNEL); + if (!alarm_events) { + ret = -ENOMEM; + goto out1; + } + ret = register_chrdev(tlclk_major, "telco_clock", &tlclk_fops); if (ret < 0) { printk(KERN_ERR "tlclk: can't get major %d.\n", tlclk_major); + kfree(alarm_events); return ret; } tlclk_major = ret; - alarm_events = kzalloc( sizeof(struct tlclk_alarms), GFP_KERNEL); - if (!alarm_events) { - ret = -ENOMEM; - goto out1; - } /* Read telecom clock IRQ number (Set by BIOS) */ if (!request_region(TLCLK_BASE, 8, "telco_clock")) { @@ -795,7 +799,6 @@ static int __init tlclk_init(void) ret = -EBUSY; goto out2; } - telclk_interrupt = (inb(TLCLK_REG7) & 0x0f); if (0x0F == telclk_interrupt ) { /* not MCPBL0010 ? */ printk(KERN_ERR "telclk_interrupt = 0x%x non-mcpbl0010 hw.\n", @@ -836,8 +839,8 @@ out3: release_region(TLCLK_BASE, 8); out2: kfree(alarm_events); -out1: unregister_chrdev(tlclk_major, "telco_clock"); +out1: return ret; }