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From: "Fāng-ruì Sòng" <maskray@google.com>
To: Florian Weimer <fw@deneb.enyo.de>
Cc: Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>,
	 Adhemerval Zanella <adhemerval.zanella@linaro.org>
Subject: Re: [PATCH] dlsym: Make RTLD_NEXT prefer default version definition [#BZ #14932]
Date: Sun, 22 May 2022 11:54:28 -0700	[thread overview]
Message-ID: <CAFP8O3J9RAg59drw-PqFW9qQ+eXngxyTssoZk8NKZz11uZyPbA@mail.gmail.com> (raw)
In-Reply-To: <87y1yw2sir.fsf@mid.deneb.enyo.de>

On Fri, May 20, 2022 at 7:22 AM Florian Weimer <fw@deneb.enyo.de> wrote:
>
> * 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.

Ok, thanks.

FWIW: I have verified that on FreeBSD 13.1, both dlsym(RTLD_NEXT,
"foo") and dlsym(RTLD_DEFAULT, "foo") resolve to the default version
definition, like what this patch does.

  reply	other threads:[~2022-05-22 18:54 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-20  8:35 Fangrui Song
2022-05-20 11:27 ` Adhemerval Zanella
2022-05-20 14:22   ` Florian Weimer
2022-05-22 18:54     ` Fāng-ruì Sòng [this message]
2022-05-27 16:59       ` Adhemerval Zanella
2022-05-27 11:03 ` Florian Weimer
2022-05-27 19:24   ` Fangrui Song
2022-05-27 20:32     ` Fangrui Song
2022-05-27 20:38       ` Florian Weimer
2022-05-27 21:03         ` Fangrui Song
2022-05-27 21:15           ` Adhemerval Zanella
2022-05-27 22:04             ` Fangrui Song

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