From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <fw@deneb.enyo.de>
Received: from albireo.enyo.de (albireo.enyo.de [37.24.231.21])
 by sourceware.org (Postfix) with ESMTPS id 17178382E2B0
 for <libc-alpha@sourceware.org>; Fri, 20 May 2022 14:22:23 +0000 (GMT)
DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 17178382E2B0
Authentication-Results: sourceware.org;
 dmarc=none (p=none dis=none) header.from=deneb.enyo.de
Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=deneb.enyo.de
Received: from [172.17.203.2] (port=38253 helo=deneb.enyo.de)
 by albireo.enyo.de ([172.17.140.2]) with esmtps
 (TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256)
 id 1ns3WG-00HJLS-OO; Fri, 20 May 2022 14:22:20 +0000
Received: from fw by deneb.enyo.de with local (Exim 4.94.2)
 (envelope-from <fw@deneb.enyo.de>)
 id 1ns3WG-0001yx-E4; Fri, 20 May 2022 16:22:20 +0200
From: Florian Weimer <fw@deneb.enyo.de>
To: Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>
Subject: Re: [PATCH] dlsym: Make RTLD_NEXT prefer default version definition
 [#BZ #14932]
References: <20220520083507.2368165-1-maskray@google.com>
 <a8ec872d-1d29-2049-03d6-74d61f4a8d7e@linaro.org>
Date: Fri, 20 May 2022 16:22:20 +0200
In-Reply-To: <a8ec872d-1d29-2049-03d6-74d61f4a8d7e@linaro.org> (Adhemerval
 Zanella via Libc-alpha's message of "Fri, 20 May 2022 08:27:53 -0300")
Message-ID: <87y1yw2sir.fsf@mid.deneb.enyo.de>
MIME-Version: 1.0
Content-Type: text/plain
X-Spam-Status: No, score=-5.9 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS,
 SPF_HELO_NONE, SPF_PASS, TXREP,
 T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
 server2.sourceware.org
X-BeenThere: libc-alpha@sourceware.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Libc-alpha mailing list <libc-alpha.sourceware.org>
List-Unsubscribe: <https://sourceware.org/mailman/options/libc-alpha>,
 <mailto:libc-alpha-request@sourceware.org?subject=unsubscribe>
List-Archive: <https://sourceware.org/pipermail/libc-alpha/>
List-Post: <mailto:libc-alpha@sourceware.org>
List-Help: <mailto:libc-alpha-request@sourceware.org?subject=help>
List-Subscribe: <https://sourceware.org/mailman/listinfo/libc-alpha>,
 <mailto:libc-alpha-request@sourceware.org?subject=subscribe>
X-List-Received-Date: Fri, 20 May 2022 14:22:24 -0000

* Adhemerval Zanella via Libc-alpha:

> On 20/05/2022 05:35, Fangrui Song via Libc-alpha wrote:
>> When the first object providing foo defines both foo@v1 and foo@@v2,
>> dlsym(RTLD_NEXT, "foo") returns foo@v1 while dlsym(RTLD_DEFAULT, "foo")
>> returns foo@@v2.  The issue is that RTLD_DEFAULT use the
>> DL_LOOKUP_RETURN_NEWEST flag while RTLD_NEXT doesn't.  Fix the RTLD_NEXT
>> branch to use DL_LOOKUP_RETURN_NEWEST.
>
> I am afraid we will need to add a compat dlsym for this change.

My working theory is dlsym with RTLD_NEXT with a versioned symbol is
so buggy that this is not needed.  I want to understand the nature of
the bug, and plan to post a write-up.