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 9150CC56202 for ; Mon, 9 Nov 2020 13:41:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CDA2206B2 for ; Mon, 9 Nov 2020 13:41:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732285AbgKINlP (ORCPT ); Mon, 9 Nov 2020 08:41:15 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:52638 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730631AbgKINjB (ORCPT ); Mon, 9 Nov 2020 08:39:01 -0500 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 1kc7Nr-0000EE-UK; Mon, 09 Nov 2020 13:38:59 +0000 From: Colin Ian King Subject: re: net: dsa: hellcreek: Add support for hardware timestamping To: Kamil Alkhouri , Kurt Kanzenbach , Richard Cochran , Jakub Kicinski Cc: Andrew Lunn , ivien Didelot , Florian Fainelli , Vladimir Oltean , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "kernel-janitors@vger.kernel.org" Message-ID: <7c4b526c-b229-acdf-d22a-2bf4a206be5b@canonical.com> Date: Mon, 9 Nov 2020 13:38:59 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 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 on linux-next with Coverity has detected a potential null pointer dereference issue on the following commit: commit f0d4ba9eff75a79fccb7793f4d9f12303d458603 Author: Kamil Alkhouri Date: Tue Nov 3 08:10:58 2020 +0100 net: dsa: hellcreek: Add support for hardware timestamping The analysis is as follows: 323 /* Get nanoseconds from ptp packet */ 324 type = SKB_PTP_TYPE(skb); 4. returned_null: ptp_parse_header returns NULL (checked 10 out of 12 times). 5. var_assigned: Assigning: hdr = NULL return value from ptp_parse_header. 325 hdr = ptp_parse_header(skb, type); Dereference null return value (NULL_RETURNS) 6. dereference: Dereferencing a pointer that might be NULL hdr when calling hellcreek_get_reserved_field. 326 ns = hellcreek_get_reserved_field(hdr); 327 hellcreek_clear_reserved_field(hdr); This issue can only occur if the type & PTP_CLASS_PMASK is not one of PTP_CLASS_IPV4, PTP_CLASS_IPV6 or PTP_CLASS_L2. I'm not sure if this is a possibility or not, but I'm assuming that it would be useful to perform the null check just in case, but I'm not sure how this affects the hw timestamping code in this function. Colin