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=-0.8 required=3.0 tests=BAYES_40, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 0E5D5C433C1 for ; Wed, 24 Mar 2021 15:37:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DDA9E619D5 for ; Wed, 24 Mar 2021 15:37:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236653AbhCXPgy (ORCPT ); Wed, 24 Mar 2021 11:36:54 -0400 Received: from lithops.sigma-star.at ([195.201.40.130]:46304 "EHLO lithops.sigma-star.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236648AbhCXPge (ORCPT ); Wed, 24 Mar 2021 11:36:34 -0400 X-Greylist: delayed 333 seconds by postgrey-1.27 at vger.kernel.org; Wed, 24 Mar 2021 11:36:34 EDT Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id 25930608F44C for ; Wed, 24 Mar 2021 16:30:59 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id 6rUQrndYfzQs for ; Wed, 24 Mar 2021 16:30:58 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id CB2CB608F448 for ; Wed, 24 Mar 2021 16:30:58 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id EOf86SEyXZur for ; Wed, 24 Mar 2021 16:30:58 +0100 (CET) Received: from lithops.sigma-star.at (lithops.sigma-star.at [195.201.40.130]) by lithops.sigma-star.at (Postfix) with ESMTP id AC7CB606BA27 for ; Wed, 24 Mar 2021 16:30:58 +0100 (CET) Date: Wed, 24 Mar 2021 16:30:58 +0100 (CET) From: Richard Weinberger To: linux-can@vger.kernel.org Message-ID: <1883346738.111675.1616599858539.JavaMail.zimbra@nod.at> Subject: Breaking UAPI change? MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [195.201.40.130] X-Mailer: Zimbra 8.8.12_GA_3807 (ZimbraWebClient - FF78 (Linux)/8.8.12_GA_3809) Thread-Index: i95Ht5GBF8pTCLR2V25CkB/f5VLg4A== Thread-Topic: Breaking UAPI change? Precedence: bulk List-ID: X-Mailing-List: linux-can@vger.kernel.org Hi! commit f5223e9eee65 ("can: extend sockaddr_can to include j1939 members") increased the size of struct sockaddr_can. This is a problem for applications which use recvfrom() with addrlen being sizeof(struct sockaddr_can) or sizeof(struct sockaddr). If such an application was built before the change it will no longer function correctly on newer kernels. In fact I ran into such a scenario and found the said commit later that day. Is this a known issue? Or is this allowed and application must not use sizeof(struct sockaddr_can) as addrlen? If so, what is the proposed way to avoid future breakage? Thanks, //richard