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Re: ia64/91846: TLS: malloc(3) exposes DTLS bug in non-threaded applications
The following reply was made to PR ia64/91846; it has been noted by GNATS.
From: Doug Rabson <dfr@xxxxxxxxxx>
To: freebsd-ia64@xxxxxxxxxxx
Cc: Marcel Moolenaar <marcel@xxxxxxxxxx>, freebsd-gnats-submit@xxxxxxxxxxx
Subject: Re: ia64/91846: TLS: malloc(3) exposes DTLS bug in non-threaded applications
Date: Mon, 16 Jan 2006 10:09:41 +0000
On Monday 16 January 2006 00:22, Marcel Moolenaar wrote:
> >Number: 91846
> >Category: ia64
> >Synopsis: TLS: malloc(3) exposes DTLS bug in non-threaded
> > applications Confidential: no
> >Severity: serious
> >Priority: medium
> >Responsible: freebsd-ia64
> >State: open
> >Quarter:
> >Keywords:
> >Date-Required:
> >Class: sw-bug
> >Submitter-Id: current-users
> >Arrival-Date: Mon Jan 16 00:30:07 GMT 2006
> >Closed-Date:
> >Last-Modified:
> >Originator: Marcel Moolenaar
> >Release: 7-CURRENT
> >Organization:
> >Environment:
>
> FreeBSD bigsur.pn.xcllnt.net 7.0-CURRENT FreeBSD 7.0-CURRENT #1: Fri
> Jan 13 16:26:27 PST 2006
> marcel@xxxxxxxxxxxxxxxxxxxx:/usr/obj/nfs/freebsd/7.x/src/sys/BIGSUR
> ia64
>
> >Description:
>
> When NO_TLS is *not* defined in src/lib/libc/stdlib/malloc.c on ia64,
> then a SIGSEGV will result due to arenas_map being thread-local and
> it being referenced in choose_arena(). That reference causes a
> thread-local relocation to end up in tls_get_addr_common() in
> src/libexec/rtld-elf/rtld.c for which the dtvp argument is NULL. This
> pretty much means that __tls_get_addr() on ia64 does the wrong thing.
> In this case it assumes that r13 (aka TP) is non-NULL in all cases,
> which is false for non-threaded applications.
I don't understand this. Any dynamic application (threaded or
non-threaded) should end up
calling .../ia64/reloc.c:allocate_initial_tls() which sets r13 to point
at the TLS block for the main thread (or only thread for non-threaded).
