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Date:      Mon, 05 Apr 2021 03:13:20 +0000
From:      bugzilla-noreply@freebsd.org
To:        bugs@FreeBSD.org
Subject:   [Bug 254774] [rtld] dl_iterate_phdr: dlpi_tls_data should be the iterated module's TLS image instead of TLS initialization image
Message-ID:  <bug-254774-227-DUT8g3hypn@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-254774-227@https.bugs.freebsd.org/bugzilla/>
References:  <bug-254774-227@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D254774

--- Comment #3 from Konstantin Belousov <kib@FreeBSD.org> ---
(In reply to Brandon Bergren from comment #2)
The drv reallocation should not affect dl_iterate_phdr() result.

That said, for dl_iterate_phdr() for dynamic binary, the fix is indeed simp=
le:
diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 733c3c80b70f..0ded117b1019 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -3909,13 +3909,16 @@ dlinfo(void *handle, int request, void *p)
 static void
 rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_inf=
o)
 {
+       tls_index ti;

        phdr_info->dlpi_addr =3D (Elf_Addr)obj->relocbase;
        phdr_info->dlpi_name =3D obj->path;
        phdr_info->dlpi_phdr =3D obj->phdr;
        phdr_info->dlpi_phnum =3D obj->phsize / sizeof(obj->phdr[0]);
        phdr_info->dlpi_tls_modid =3D obj->tlsindex;
-       phdr_info->dlpi_tls_data =3D obj->tlsinit;
+       ti.ti_module =3D obj->tlsindex;
+       ti.ti_offset =3D 0;
+       phdr_info->dlpi_tls_data =3D __tls_get_addr(&ti);
        phdr_info->dlpi_adds =3D obj_loads;
        phdr_info->dlpi_subs =3D obj_loads - obj_count;
 }

But for static binary where libc TLS implementation is used, we do not prov=
ide
working __tls_get_addr().  Do you need this for static binaries, or it would
be only the consistency that is hurt if libc implementation is provided lat=
er?

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