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 EBBECC07E95 for ; Mon, 19 Jul 2021 15:48:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D304861264 for ; Mon, 19 Jul 2021 15:48:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345073AbhGSPHu (ORCPT ); Mon, 19 Jul 2021 11:07:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:38384 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346238AbhGSPFX (ORCPT ); Mon, 19 Jul 2021 11:05:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id AD034601FD; Mon, 19 Jul 2021 15:46:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626709562; bh=DWpobaDPfgHnuXOwwpkJpmQtmK/C8RWhGYIPMsqcv3s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HSfcDNsQcdVaip75XocwT2jY0tcKQPPsDh4K3LetuSVKpQ1TQj8CD2cM54NW6/2Lg 7uOfFlKdjM9s1M2Iu+K1uuDgZ1XkvyGC+ZXVC/B9GJ2txA5ypO/iBKv090ZVb/j1g2 cSS9tzZK48I+bVqNRLrvv5FGvyvhp1l8LNyXoVRg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sherry Sun , Sasha Levin Subject: [PATCH 5.4 011/149] tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero Date: Mon, 19 Jul 2021 16:51:59 +0200 Message-Id: <20210719144904.076804878@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144901.370365147@linuxfoundation.org> References: <20210719144901.370365147@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 6ad985e8dc65..b053345dfd1a 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -2253,6 +2253,9 @@ 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