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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 CB228C43460 for ; Fri, 9 Apr 2021 13:27:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 92DAB6115C for ; Fri, 9 Apr 2021 13:27:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233598AbhDIN1r (ORCPT ); Fri, 9 Apr 2021 09:27:47 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:46670 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231599AbhDIN1q (ORCPT ); Fri, 9 Apr 2021 09:27:46 -0400 Received: from 1.general.cking.uk.vpn ([10.172.193.212]) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lUrAZ-00019X-TV; Fri, 09 Apr 2021 13:27:31 +0000 To: Siva Reddy , Byungho An From: Colin Ian King Subject: net: sxgbe: issue with incorrect masking / case values in switch statements Cc: Vipul Pandya , Girish K S , "David S. Miller" , Jakub Kicinski , "netdev@vger.kernel.org" Message-ID: Date: Fri, 9 Apr 2021 14:27:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi, Static analysis with Coverity has found an issue with the sxgbe driver in drivers/net/ethernet/samsung/sxgbe/sxgbe_mtl.c from the following commit: commit 1edb9ca69e8a7988900fc0283e10550b5592164d Author: Siva Reddy Date: Tue Mar 25 12:10:54 2014 -0700 net: sxgbe: add basic framework for Samsung 10Gb ethernet driver The analysis is as follows: 20 static void sxgbe_mtl_init(void __iomem *ioaddr, unsigned int etsalg, 21 unsigned int raa) 22 { 23 u32 reg_val; 24 25 reg_val = readl(ioaddr + SXGBE_MTL_OP_MODE_REG); 26 reg_val &= ETS_RST; 27 28 /* ETS Algorith */ 29 switch (etsalg & SXGBE_MTL_OPMODE_ESTMASK) { Logically dead code (DEADCODE) 30 case ETS_WRR: 31 reg_val &= ETS_WRR; 32 break; Logically dead code (DEADCODE) 33 case ETS_WFQ: 34 reg_val |= ETS_WFQ; 35 break; Logically dead code (DEADCODE) 36 case ETS_DWRR: 37 reg_val |= ETS_DWRR; 38 break; 39 } Above: SXGBE_MTL_OPMODE_ESTMASK is 0x3 ETS_WRR is 0xFFFFFFFB ETS_WFQ is 0x00000020 ETS_DWRR is 0x00000040 so none of the case statements are ever reachable because of the mask being used. 40 writel(reg_val, ioaddr + SXGBE_MTL_OP_MODE_REG); 41 42 switch (raa & SXGBE_MTL_OPMODE_RAAMASK) { Logically dead code (DEADCODE) 43 case RAA_SP: 44 reg_val &= RAA_SP; 45 break; Logically dead code (DEADCODE) 46 case RAA_WSP: 47 reg_val |= RAA_WSP; 48 break; 49 } 50 writel(reg_val, ioaddr + SXGBE_MTL_OP_MODE_REG); 51} And above, SXGBE_MTL_OPMODE_RAAMASK is 0x1 RAA_SP is 0xFFFFFFFB RAA_WSP is 0x00000004 again, none of the case statements are ever reachable because of the mask being used. Not sure of how this was meant to work, so I can't determine a fix, hence I'm reporting this issue. Colin