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Re: [PATCH] Remove debug/stack_chk_fail_local.c [BZ #21740]
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Nick Alcock <nick dot alcock at oracle dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Mon, 10 Jul 2017 06:14:01 -0700
- Subject: Re: [PATCH] Remove debug/stack_chk_fail_local.c [BZ #21740]
- Authentication-results: sourceware.org; auth=none
- References: <20170709154233.GA10935@gmail.com> <87d198lg6d.fsf@esperi.org.uk>
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