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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 8DF7BC07E9C for ; Sat, 10 Jul 2021 02:25:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 788CC613AF for ; Sat, 10 Jul 2021 02:25:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232553AbhGJC2N (ORCPT ); Fri, 9 Jul 2021 22:28:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:43192 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233662AbhGJC1h (ORCPT ); Fri, 9 Jul 2021 22:27:37 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 33276613D1; Sat, 10 Jul 2021 02:24:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625883879; bh=gLr8AGwzad/+lkLaGkCkTb6n2SoLCd488fNl48G1pGw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OQrpfU87OUQRJ3ad8U+RVs/A9z28PaR6hZuiWpz0XA4NCblxpZ6HJn2xy/kJ7z8Qp DHHrsft8EMtc8GzzjUrs+fsLis3tuvLgzLfbt4lkvmDitIayWdisf3fbsQNRrtteM4 uf53keE4JjKDSSpWonJQGXIbFbfdWJSmVQdNckAvahFrIL2fIRIZquIVu3yx765/d/ 1bPIw27aa/XuVBMI7dwc3JI50wFZSu9Zhnx/PzdVKUbTJHHni52wCTObrDr8b/DvZF q4o9UBLCAFBBPBgx/XDunfZ1M2yYDUwTjVf7QzxJZVsIxi2ALJrMoC9CV1wLJPm4Bo p7e05TN3syHrw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sherry Sun , Greg Kroah-Hartman , Sasha Levin , linux-serial@vger.kernel.org Subject: [PATCH AUTOSEL 5.10 08/93] tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero Date: Fri, 9 Jul 2021 22:23:02 -0400 Message-Id: <20210710022428.3169839-8-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210710022428.3169839-1-sashal@kernel.org> References: <20210710022428.3169839-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-serial@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 bd047e1f9bea..7aab87c92192 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -2414,6 +2414,9 @@ 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 = lpuart_get_baud_clk_rate(sport); /* -- 2.30.2