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=unavailable 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 70B59C07E9B for ; Sat, 10 Jul 2021 02:18:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 59DDA613D6 for ; Sat, 10 Jul 2021 02:18:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232016AbhGJCVG (ORCPT ); Fri, 9 Jul 2021 22:21:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:37244 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231856AbhGJCUu (ORCPT ); Fri, 9 Jul 2021 22:20:50 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1B569613C3; Sat, 10 Jul 2021 02:18:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625883485; bh=+9UPDC3W+FxbL0Fh0wF+dzwqqgzFRZAhf/9SCoD6MX8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oRBogecCrwbJuMdYXWgMaeap4J20FFFOL5fGUzzWoqVDhCGdg4q1BY5yIE4HjbX2r LsNvRuQQUI6d0t5pedR1o/FnXUTZ1wnEoZjesM8jcZ93CjZPSa5O2yr57+QsPzryjc Ndl/R9uPKv9GdZAZknwIFtGGmMMmxYtXPS9BE+E0/R5c1LjisfbzOMyKtXgDA2yGTy knvQP2VZbgr5Y6ROKTgWkfEAznZ5meEFUZ+UQMfzpydbwn86b2I5QqsOtIR99Stxnp ZTw1Idrs7e9+AX0xh6zaN3KOEZMXlQG/bnK0gyhksw0CnNxKI7C04aAYBxkK1IUa1+ isXc4bMYPKluQ== 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 5.13 011/114] tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero Date: Fri, 9 Jul 2021 22:16:05 -0400 Message-Id: <20210710021748.3167666-11-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210710021748.3167666-1-sashal@kernel.org> References: <20210710021748.3167666-1-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-kernel@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 794035041744..777d54b593f8 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -2414,6 +2414,9 @@ 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