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 19332C07E99 for ; Sat, 10 Jul 2021 02:28:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F36E2613ED for ; Sat, 10 Jul 2021 02:28:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232516AbhGJCba (ORCPT ); Fri, 9 Jul 2021 22:31:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:48492 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232756AbhGJC36 (ORCPT ); Fri, 9 Jul 2021 22:29:58 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8088F613E6; Sat, 10 Jul 2021 02:27:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625884034; bh=DWpobaDPfgHnuXOwwpkJpmQtmK/C8RWhGYIPMsqcv3s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Jh971ZJYPElgjzrDMu3feorwwBXXocn6wQE9D6Up7VYlbEjbveZ+FxMPBt0h84Mxh x4ziG2/faQu+zKoq6tuvDJtMghNqvHh5jVM6vdWkutRzhmBD4433pIHL3/KOMEK2Uz aGlq/7raKDGN3C2OEich4Go3ZN1vmjB2UW2ZMlrlWo3jIo/R/M5dGS9aC939hg6qrL MHkeU3ufkuUFCi9UmT/l0kRoaKzCu9EY3YbzxuVDWMhj/Ed/W1qcVMo+ZdiVAt1h9Q s5yiU4pswc3vF71sFKDM3QprSyGAb1rY/OvgxRyEFBYy0MQOtgq2vonN3FaPsVFmrK aaHMRw2/mt0fw== 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 5.4 03/63] tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero Date: Fri, 9 Jul 2021 22:26:09 -0400 Message-Id: <20210710022709.3170675-3-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210710022709.3170675-1-sashal@kernel.org> References: <20210710022709.3170675-1-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 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