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=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 69FF6C07E95 for ; Mon, 19 Jul 2021 15:33:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 556C561353 for ; Mon, 19 Jul 2021 15:33:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238839AbhGSOww (ORCPT ); Mon, 19 Jul 2021 10:52:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:40962 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245519AbhGSOrj (ORCPT ); Mon, 19 Jul 2021 10:47:39 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D8AC5613B7; Mon, 19 Jul 2021 15:24:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626708243; bh=RziDAp4BQsITzVInvhjMeZNe1otkpJ26f5BdXuv1mXc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XTohieLbjTQrmB5Jz7i7zuS7YK4JCZMiywG7LKK0coXyznt89lHQpPxOvY06OhfyQ f4ljvvWkt3U6UG1pU/oo+gQ0GvKAHdRlwF1ySuUNFa9pfSFv04vqCIoC4ZBVAw10db c7KPnJy1jPbiR0xgLMBnVDgLr9kLENkcGax/rOd0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sherry Sun , Sasha Levin Subject: [PATCH 4.14 236/315] tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero Date: Mon, 19 Jul 2021 16:52:05 +0200 Message-Id: <20210719144951.183528031@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144942.861561397@linuxfoundation.org> References: <20210719144942.861561397@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sherry Sun [ Upstream commit fcb10ee27fb91b25b68d7745db9817ecea9f1038 ] We should be very careful about the register values that will be used for division or modulo operations, althrough the possibility that the UARTBAUD register value is zero is very low, but we had better to deal with the "bad data" of hardware in advance to avoid division or modulo by zero leading to undefined kernel behavior. Signed-off-by: Sherry Sun Link: https://lore.kernel.org/r/20210427021226.27468-1-sherry.sun@nxp.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/fsl_lpuart.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index cebebdcd091c..3d5fe53988e5 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1998,6 +1998,9 @@ lpuart32_console_get_options(struct lpuart_port *sport, int *baud, bd = lpuart32_read(&sport->port, UARTBAUD); bd &= UARTBAUD_SBR_MASK; + if (!bd) + return; + sbr = bd; uartclk = clk_get_rate(sport->clk); /* -- 2.30.2