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=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 5D229C6499C for ; Mon, 19 Jul 2021 17:59:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 422E66115B for ; Mon, 19 Jul 2021 17:59:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347088AbhGSRSA (ORCPT ); Mon, 19 Jul 2021 13:18:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:34630 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344337AbhGSPlU (ORCPT ); Mon, 19 Jul 2021 11:41:20 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 102E4613F7; Mon, 19 Jul 2021 16:21:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626711661; bh=N0b5EA01m6rix3zjJGI/CI/y5V9fr1n/JREdGLiscwk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2NtXbQJN2Ao68lSemN7N9Ip/oGQo3NwmsVoPG8WPYV41uKzOdXwX5vgeEkIhl6LRI zY0f4uTCa8ajYJY4uhZ415FcWEonWV0GwqATSx9tBv9Az/MO9bhJ/W2XFuwRzUA7Kn X14xDJkgjkyrwYBRnUstb7qdG/O9YTsLTnrwizLw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sherry Sun , Sasha Levin Subject: [PATCH 5.12 041/292] tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero Date: Mon, 19 Jul 2021 16:51:43 +0200 Message-Id: <20210719144943.866461330@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144942.514164272@linuxfoundation.org> References: <20210719144942.514164272@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: linux-kernel@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 9c78e43e669d..4cad2ac00e9f 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -2404,6 +2404,9 @@ 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