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 36651C07E9B for ; Sat, 10 Jul 2021 02:38:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 20C26613CA for ; Sat, 10 Jul 2021 02:38:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234834AbhGJClO (ORCPT ); Fri, 9 Jul 2021 22:41:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:58382 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235806AbhGJCjr (ORCPT ); Fri, 9 Jul 2021 22:39:47 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A2C8961419; Sat, 10 Jul 2021 02:36:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625884566; bh=6IIqv45VZhMDWIeJ4VV/kuRvyK4QUeRR9GmrKQlpsBA=; h=From:To:Cc:Subject:Date:From; b=LFMhW7wZ9NCOuhd2sQ9HEsZaB2GXPuTo76Y4/2IRJAZtHLJILSU0Mh45ltYyP5GsA n4Ci7nQpVvwG0BDih4UNAQFczNrDefG7ncRla4cGYzbXf2Osz2mW2Osf5WDp267G0F +5fxq7c83rgOgZcJq+I2HKHWixMOTCAkxU8NCdxeSFWnnHMfRWZ1ySnFR87HCRuye2 K1AKlf4bsA0lIdgSG43YraxJySnjEfE1kgIvz05gt7H1wvxhBqzotPmBnLbhDtZwEr H0OfgVxQeR+QAKgR0SIUZWKVn77PGow1hEjWWm8Ewe0RY32EIlNYG1qFbTR0ukC7Jo ASd8IiZyUkaaQ== 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 4.9 01/26] tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero Date: Fri, 9 Jul 2021 22:35:39 -0400 Message-Id: <20210710023604.3172486-1-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 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 5b6093dc3ff2..a4c1797e30d7 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1766,6 +1766,9 @@ lpuart32_console_get_options(struct lpuart_port *sport, int *baud, bd = lpuart32_read(sport->port.membase + UARTBAUD); bd &= UARTBAUD_SBR_MASK; + if (!bd) + return; + sbr = bd; uartclk = clk_get_rate(sport->clk); /* -- 2.30.2