From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by sourceware.org (Postfix) with ESMTPS id 5BC6A387221D for ; Tue, 13 Dec 2022 18:32:12 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 5BC6A387221D Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pj1-x102d.google.com with SMTP id e7-20020a17090a77c700b00216928a3917so4469429pjs.4 for ; Tue, 13 Dec 2022 10:32:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=02Up62cJkd8fVbpMXPEJvRczXHzoVDnWmP9CFlSGCgI=; b=kSiFYQ3BefgQDVkCguvH7XJAVRAn8hNM9g0gLCSrbd7tbKxPTTglOPxwc/DJjOLaoQ M7iqLB2e/xJrKeCIcgBb28oQbfin/CZklY7lobYnWrTWbe8kTHkWoFdQTx5r5NtvfGIk //fv5ppYt+OVnpUXaH7+ilNh9xFKhhevF9U0HuEM0ntSXdVKmoVIDiTQXSBBEHkvmb0s wqxfLbWR/1hNYS6/w70bgSQhVUJaBZGVVN2j7tNsX6w4hgsMimJXQOGqSzCqdYvxODKA QKw2xsNdZfrj4dRqxp/MVSwUFQ4kn7W+YT/Yip/cBl3pMpVDBoSmVg4aL21xVCRXhz6H MQDw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=02Up62cJkd8fVbpMXPEJvRczXHzoVDnWmP9CFlSGCgI=; b=jyRfsEsoQyk1oUnyHiEotmeGnkhQMebe8UyTIOFHfgk/zMN+WrziVvfrJ2K0F62+lH mwncMFUkz4oYacFpSc63lUd96AXy7yDyAnex/9uhuVGXR8IOvOVjKagMy7YS8wNFz/uv xvIlU76eKxsDle9VCo/6BFfUjIp3CdloC8OmiqleSmZzq0R23LIMZSETduewQvb7DdLY WkppbLC/aBsVQM/nX0Zy5wjaOdQ5wozMyx8/+20DE69Vbrl/jQv5i4LuWmMlbdQFcGv1 3P4OAR94D15APRotT9yDJmL/199mamPOigf77hPHDOe4cBdbfvg8wFP9pNCFP7F9DT1V MOIw== X-Gm-Message-State: ANoB5pnnLkCcpRuo7OhyUrbQNdwGYrOZll2EFP1+Lrx1LGuviYq2lasc p/F2blX/93vZaHdJs0sL2k/c0IkCQ4O5Zpf+64oUOM+XSCo= X-Google-Smtp-Source: AA0mqf7KoU4KbTSUV7KIXyVCpnrqTxNgsUjXNtW5K+hrkdeYmNgN6VJv11xVKr67fkyHQL7iVuXPRQndyVfbnGBFoNo= X-Received: by 2002:a17:90a:f3d2:b0:219:f8ee:c7fc with SMTP id ha18-20020a17090af3d200b00219f8eec7fcmr552756pjb.163.1670956331439; Tue, 13 Dec 2022 10:32:11 -0800 (PST) MIME-Version: 1.0 References: <0a1f01d90f1f$96c7ce60$c4576b20$@yottadb.com> In-Reply-To: <0a1f01d90f1f$96c7ce60$c4576b20$@yottadb.com> From: Andrew Pinski Date: Tue, 13 Dec 2022 10:31:59 -0800 Message-ID: Subject: Re: Bug 29863 - Segmentation fault in memcmp-sse2.S if memory contents can concurrently change To: Narayanan Iyer Cc: libc-alpha@sourceware.org Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-1.6 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Tue, Dec 13, 2022 at 10:21 AM Narayanan Iyer via Libc-alpha wrote: > > Hi, > > I had created a glibc bug report at https://sourceware.org/bugzilla/show_bug.cgi?id=29863 > > And have included the title of that report in the email subject as well. > > It has been a week since I created the issue and I did not hear anything back. I believe this is a regression in glibc 2.36 and have provided enough information in the bug report (along with the commit that caused the regression). I don't see how this is a valid well defined testcase. Changing memory without barriers in both threads is not well defined. memcmp is not guaranteed to be atomic or have any atomicity either. So you just happen to work before and now your undefined code does not work. Thanks, Andrew Pinski > > Given the upcoming glibc 2.37 release, I was asked (by Carlos O'Donell ) to raise it on this mailing list to get the attention of the glibc developers. > > I am hoping one of you could take a quick look at the bug report and see if it is worth fixing it in time for glibc 2.37. > > Thanks, > Narayanan. > >