Re: [PATCH] Remove debug/stack_chk_fail_local.c [BZ #21740]

["H.J. Lu" <hjl.tools@gmail.com>]

On Mon, Jul 10, 2017 at 11:50:02AM +0100, Nick Alcock wrote:
> On 9 Jul 2017, H. J. Lu verbalised:
> 
> > Since
> >
> > commit 524a8ef2ad76af8ac049293d993a1856b0d888fb
> > Author: Nick Alcock <nick.alcock@oracle.com>
> > Date:   Mon Dec 26 10:08:57 2016 +0100
> >
> >     PLT avoidance for __stack_chk_fail [BZ #7065]
> >
> >     Add a hidden __stack_chk_fail_local alias to libc.so,
> >     and make sure that on targets which use __stack_chk_fail,
> >     this does not introduce a local PLT reference into libc.so.
> >
> > added
> >
> > strong_alias (__stack_chk_fail, __stack_chk_fail_local)
> >
> > to debug/stack_chk_fail.c, debug/stack_chk_fail_local.c should be
> > removed.
> >
> > OK for master?
> 
> If it passes a test build with --enable-stack-protector=all without
> pulling junk into ld.so and exploding at ld.so link time, sure. (That's
> what happened every time I tried to remove this stuff before, but I may
> have failed to notice that this may not be necessary any more.)

Here is the updated patch.  tst-_dl_addr_inside_object should be
linked with $(dummy-stack-chk-fail).  Otherwise, __stack_chk_fail is
undefined.  OK for master branch?

> 
> > -/* On some architectures, this helps needless PIC pointer setup
> > -   that would be needed just for the __stack_chk_fail call.  */
> 
> Does anyone know what architectures these might be? Presumably x86-32...
> 

config/i386/i386.c:   __stack_chk_fail_local hidden function instead of calling
config/powerpcspe/powerpcspe.c:   setup by using __stack_chk_fail_local hidden function instead of
config/rs6000/rs6000.c:   setup by using __stack_chk_fail_local hidden function instead of


H.J.
--
From 712e70de9743a61618001b4c6372a0e3d4fc1d90 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Sun, 9 Jul 2017 08:39:17 -0700
Subject: [PATCH] Remove debug/stack_chk_fail_local.c [BZ #21740]

Since

commit 524a8ef2ad76af8ac049293d993a1856b0d888fb
Author: Nick Alcock <nick.alcock@oracle.com>
Date:   Mon Dec 26 10:08:57 2016 +0100

    PLT avoidance for __stack_chk_fail [BZ #7065]

    Add a hidden __stack_chk_fail_local alias to libc.so,
    and make sure that on targets which use __stack_chk_fail,
    this does not introduce a local PLT reference into libc.so.

added

strong_alias (__stack_chk_fail, __stack_chk_fail_local)

to debug/stack_chk_fail.c, debug/stack_chk_fail_local.c should be
removed.  Since dummy __stack_chk_fail and __stack_chk_fail_local
symbols are used in ld.so, tst-_dl_addr_inside_object should be
linked with $(dummy-stack-chk-fail).   Tested on x86-64 with
--enable-stack-protector=all and got

FAIL: elf/tst-env-setuid
FAIL: elf/tst-env-setuid-tunables
FAIL: stdlib/tst-secure-getenv

which are the same as without this patch.

	* [BZ #21740]
	* debug/Makefile (static-only-routines): Remove
	stack_chk_fail_local.
	* debug/stack_chk_fail_local.c: Removed.
	* elf/Makefile (LDFLAGS-tst-_dl_addr_inside_object): New.
---
 debug/Makefile               |  2 +-
 debug/stack_chk_fail_local.c | 46 --------------------------------------------
 elf/Makefile                 |  1 +
 3 files changed, 2 insertions(+), 47 deletions(-)
 delete mode 100644 debug/stack_chk_fail_local.c

diff --git a/debug/Makefile b/debug/Makefile
index cd4975c..136c9a1 100644
--- a/debug/Makefile
+++ b/debug/Makefile
@@ -51,7 +51,7 @@ routines  = backtrace backtracesyms backtracesymsfd noophooks \
 	    explicit_bzero_chk \
 	    stack_chk_fail fortify_fail \
 	    $(static-only-routines)
-static-only-routines := warning-nop stack_chk_fail_local
+static-only-routines := warning-nop
 
 # Building the stack-protector failure routines with stack protection
 # makes no sense.
diff --git a/debug/stack_chk_fail_local.c b/debug/stack_chk_fail_local.c
deleted file mode 100644
index eb0a759..0000000
--- a/debug/stack_chk_fail_local.c
+++ /dev/null
@@ -1,46 +0,0 @@
-/* Copyright (C) 2005-2017 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   In addition to the permissions in the GNU Lesser General Public
-   License, the Free Software Foundation gives you unlimited
-   permission to link the compiled version of this file with other
-   programs, and to distribute those programs without any restriction
-   coming from the use of this file. (The GNU Lesser General Public
-   License restrictions do apply in other respects; for example, they
-   cover modification of the file, and distribution when not linked
-   into another program.)
-
-   Note that people who make modified versions of this file are not
-   obligated to grant this special exception for their modified
-   versions; it is their choice whether to do so. The GNU Lesser
-   General Public License gives permission to release a modified
-   version without this exception; this exception also makes it
-   possible to release a modified version which carries forward this
-   exception.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <http://www.gnu.org/licenses/>.  */
-
-#include <sys/cdefs.h>
-
-extern void __stack_chk_fail (void) __attribute__ ((noreturn));
-
-/* On some architectures, this helps needless PIC pointer setup
-   that would be needed just for the __stack_chk_fail call.  */
-
-void __attribute__ ((noreturn)) attribute_hidden
-__stack_chk_fail_local (void)
-{
-  __stack_chk_fail ();
-}
diff --git a/elf/Makefile b/elf/Makefile
index e758a4c..fb2d855 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -369,6 +369,7 @@ tests-internal += tst-_dl_addr_inside_object
 tests-pie += tst-_dl_addr_inside_object
 $(objpfx)tst-_dl_addr_inside_object: $(objpfx)dl-addr-obj.os
 CFLAGS-tst-_dl_addr_inside_object.c += $(PIE-ccflag)
+LDFLAGS-tst-_dl_addr_inside_object = $(dummy-stack-chk-fail)
 endif
 
 # By default tst-linkall-static should try to use crypt routines to test
-- 
2.9.4