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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 B3491C54FCB for ; Sat, 25 Apr 2020 16:15:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B57E20704 for ; Sat, 25 Apr 2020 16:15:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="DzBb0A+o" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726125AbgDYQPm (ORCPT ); Sat, 25 Apr 2020 12:15:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726076AbgDYQPl (ORCPT ); Sat, 25 Apr 2020 12:15:41 -0400 Received: from mail-ej1-x644.google.com (mail-ej1-x644.google.com [IPv6:2a00:1450:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F861C09B04D for ; Sat, 25 Apr 2020 09:15:41 -0700 (PDT) Received: by mail-ej1-x644.google.com with SMTP id e2so10047053eje.13 for ; Sat, 25 Apr 2020 09:15:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:reply-to:from:date:message-id :subject:to:cc; bh=0WiVwyuEQkAYfke5GAs2kMxX4Q59OqUoiQYXMOh2hJc=; b=DzBb0A+oQCfqqsLX1dGEHlRAg5ieQv/YZGzgvciwTk62Kcr62Vs1TXJfgjUEeLG6s2 GHPXpmXFoK/9xsjLOw4DXizAL/lrzHQ9V3OiLiJ0c2pieZJ4tiZnCgEAGZElKN4oaq0i P/+M9WqcmHxCjP09O0fYEzebwk7seCzAL7xRL1CA/sIZGePWVIRj+uZEA3Xg9KauHPsm Gmnz+/QmlZmPWq7g1k+VpUZMuNhFYkq2nkkPFcQcMygSjXp89QZVSepT76x+a5y4fEVx OVVZkf0Xr1nogsA1TscErIFaSJ7oE7XgXnGRpq9V+LrhaBAn/Kvs4tG1EBwfaYDp3+/c rCrQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:reply-to :from:date:message-id:subject:to:cc; bh=0WiVwyuEQkAYfke5GAs2kMxX4Q59OqUoiQYXMOh2hJc=; b=bfasdtWYS3tVtUIk9saVkPGJmwTVstukbvKlnNL5WC11jFSNACqHD2ng4EPKGdGirZ NfxbSAuRuJo+27n1bga8/gzEcU9+2/y/BXqoL1UBtf/yE+2YSVr8cwPuQsCUvIqzs7I1 M25gRNG2vknXRfuCkfzMgTevbAl2FQ6a+pqslnpbQox12E2Z+D/ZJW0GjeQx0RkR5tuR VpCY3LON215cf+OumRucVZuye8DCX9GWZmSciTaaDK2yQSD5KUTU4jFtRNzNg2QyUllQ wAmkaRYfla62FkpKRolNa/dbXq8vr+xVvZJbJaV+0gJ+o4pvaGNc1ZihMxvOmHkuXoLy 0t5g== X-Gm-Message-State: AGi0PuZyjoTZguG/DKO51xb84JC3oe1QyJ3o3PFwSExic/qs5C608ZYb ZJsvgmTqhXUGs+Do9Oo4c4vzpyTkIGte9Z0FuhVSKA== X-Google-Smtp-Source: APiQypIJk5ZjVy3GTNabL95ydemzougIu46PVSLuZne0Xy15fgQyB1KTI+xcB6YHop4xFWLAoshGxKGI9hZIhNIoMJc= X-Received: by 2002:a17:906:5fd2:: with SMTP id k18mr12022545ejv.243.1587831340343; Sat, 25 Apr 2020 09:15:40 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: Reply-To: mtk.manpages@gmail.com From: "Michael Kerrisk (man-pages)" Date: Sat, 25 Apr 2020 18:15:29 +0200 Message-ID: Subject: Re: [patch] strtok.3 add note about glibc-2.25+ segfault for call like strtok_r(NULL,"|",NULL) To: Marcin Stolarek Cc: linux-man , wdijkstr@arm.com Content-Type: text/plain; charset="UTF-8" Sender: linux-man-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org On Sat, 25 Apr 2020 at 14:52, Marcin Stolarek wrote: > > The change in glibc commit d58ab810a6e325cc351684d174c48cabce01bcc1 > (author in CC): > > From commit description:"[...] Also avoid an unnecessary call to > strcspn after the last token by adding an early exit for an empty > string.[...]" > > Important code change: > /* Parse S into tokens separated by characters in DELIM. > @@ -45,11 +41,17 @@ > char * > __strtok_r (char *s, const char *delim, char **save_ptr) > { > - char *token; > + char *end; > > if (s == NULL) > s = *save_ptr; > > + if (*s == '\0') > + { > + *save_ptr = s; > + return NULL; > + } > + > > may result in the mentioned segmentation fault if the char *str passed > to strtok_r is a NULL (for 1st call). I'm a little puzzled here. Getting a segfault if the first argument to strtok_r() is NULL on the first call seems not so surprising to me. Why would you expect otherwise? What am I missing? Thanks, Michael