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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 78566C3A59F for ; Mon, 19 Aug 2019 06:34:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4A3CC20851 for ; Mon, 19 Aug 2019 06:34:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726295AbfHSGex (ORCPT ); Mon, 19 Aug 2019 02:34:53 -0400 Received: from mail.monom.org ([188.138.9.77]:57976 "EHLO mail.monom.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725536AbfHSGex (ORCPT ); Mon, 19 Aug 2019 02:34:53 -0400 Received: from mail.monom.org (localhost [127.0.0.1]) by filter.mynetwork.local (Postfix) with ESMTP id 2C91E5005CF; Mon, 19 Aug 2019 08:34:51 +0200 (CEST) Received: from [192.168.154.174] (b9168f76.cgn.dg-w.de [185.22.143.118]) by mail.monom.org (Postfix) with ESMTPSA id EDFAB500294; Mon, 19 Aug 2019 08:34:50 +0200 (CEST) Subject: Re: [PATCH rt-tests v0 1/4] pmqtest: Increase buffer to avoid overflow To: Sebastian Andrzej Siewior Cc: Clark Williams , John Kacur , linux-rt-users@vger.kernel.org References: <20190816064204.6339-1-wagi@monom.org> <20190816064204.6339-2-wagi@monom.org> <20190816154132.xk5u7di6d5jdzw5v@linutronix.de> From: Daniel Wagner Message-ID: Date: Mon, 19 Aug 2019 08:34:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190816154132.xk5u7di6d5jdzw5v@linutronix.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-rt-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org On 8/16/19 5:41 PM, Sebastian Andrzej Siewior wrote: > On 2019-08-16 08:42:01 [+0200], Daniel Wagner wrote: >> Increase the size of the char buffer. gcc 9.1.1 reports: >> >> src/pmqtest/pmqtest.c: In function ‘main’: >> src/pmqtest/pmqtest.c:46:21: warning: ‘%d’ directive writing between 1 and 10 bytes into a region of size 8 [-Wformat-overflow=] >> 46 | #define SYNCMQ_NAME "/syncmsg%d" >> | ^~~~~~~~~~~~ >> >> src/pmqtest/pmqtest.c:445:3: note: ‘sprintf’ output between 10 and 19 bytes into a destination of size 16 >> 445 | sprintf(mqname, SYNCMQ_NAME, i); >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> >> Signed-off-by: Daniel Wagner >> --- >> src/pmqtest/pmqtest.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/src/pmqtest/pmqtest.c b/src/pmqtest/pmqtest.c >> index a04fc49872bf..20164c8d547f 100644 >> --- a/src/pmqtest/pmqtest.c >> +++ b/src/pmqtest/pmqtest.c >> @@ -440,7 +440,7 @@ int main(int argc, char *argv[]) >> goto nomem; >> >> for (i = 0; i < num_threads; i++) { >> - char mqname[16]; >> + char mqname[32]; > > The compiler says, based on SYNCMQ_NAME's size and maximum possible %d > we will have 19 bytes max. Why do you change it to 32? Why it is not > wrong, one might ask what the extra storage is for. I was taking the 16 bytes value as reference and doubled it. Indeed, 19 bytes would be a better choice. Let me refresh the series.