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 51CCDC07E9D for ; Mon, 19 Jul 2021 15:43:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3E18361351 for ; Mon, 19 Jul 2021 15:43:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344029AbhGSPDD (ORCPT ); Mon, 19 Jul 2021 11:03:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:59668 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245702AbhGSPAw (ORCPT ); Mon, 19 Jul 2021 11:00:52 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D0D9660238; Mon, 19 Jul 2021 15:41:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626709291; bh=jubVaQRlhNSmiN+XmTt572cEjRXXkVgH+Bp7bvrT6Vg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ne5x1uPgQ9PSIqYXNHBnIpzyRO8fhFWpEtDGKXpB+mq9URRojd8wVPUhpf5FjFv0C IdFy9hdjtOjcgsLGGAiWKlGUwm4MW9W18gRy4jIn0p6zrtvrzdA6W9hTSKOheqydT5 JZt1qIvj02dcTydXl6zKwNYBTGlT99316teQb1eA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sherry Sun , Sasha Levin Subject: [PATCH 4.19 323/421] tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero Date: Mon, 19 Jul 2021 16:52:14 +0200 Message-Id: <20210719144957.503921919@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144946.310399455@linuxfoundation.org> References: <20210719144946.310399455@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 4b9f42269477..deb9d4fa9cb0 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1992,6 +1992,9 @@ 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