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 87D73C11F67 for ; Sat, 10 Jul 2021 02:33:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C97E6124C for ; Sat, 10 Jul 2021 02:33:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234602AbhGJCfp (ORCPT ); Fri, 9 Jul 2021 22:35:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:53326 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235644AbhGJCe5 (ORCPT ); Fri, 9 Jul 2021 22:34:57 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9BCF26124C; Sat, 10 Jul 2021 02:32:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625884326; bh=jubVaQRlhNSmiN+XmTt572cEjRXXkVgH+Bp7bvrT6Vg=; h=From:To:Cc:Subject:Date:From; b=JbONIqs5EynXwNL7RjgaOGjuP7BVbgW1N0Pt1yUkiR2abyRLO1aCRCWrejKGa3Otx 6fjzA2IGLzgRDUr5X+9AuSRhppXZnV8XgNwzt/eb7GqPxcnA4FfZ/RnicKMTvCQd0O UWPc3zB4cFcC3GH5Tnk34nhg+XfzEgxGQVzVvR008G8CuOhYCOzAYCHylyyyn06Pit MklNqLg9DbtQIJuuz5EROreiy7WyGgE3GC9c8pBCF3mvY4oMBMVCYrw8OuJTp+auP5 3UqWXbF/nMJp/OYybbT4K/L3gLG+pSTiLMxkOEIxXBy4dzH+DqE4Rg+hJywpqEGytE ULQRKhXrKx6mg== 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 4.19 01/39] tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero Date: Fri, 9 Jul 2021 22:31:26 -0400 Message-Id: <20210710023204.3171428-1-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 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