This is the mail archive of the libc-alpha@sourceware.org mailing list for the glibc project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH] PR dynamic-link/17711: copy relocations against protected symbols don't work


On Fri, Feb 27, 2015 at 1:35 PM, Roland McGrath <roland@hack.frob.com> wrote:
>> Protocted symbol in shared library can only be accessed from PIE
>> or shared library.  Linker in binutils 2.26 enforces it.  We must
>> compile vismain with -fPIE and link it with -pie.  OK for master?
>
> Add some comments (in vismain.c is probably fine) explaining that it must
> be a PIE and why.
>
>>       PR dynamic-link/17711
>         [BZ #17711]
>
>>       * elf/Makefile (tests): Add vismain only if PIE is enabled.
>>       (tests-pie): Add vismain.
>>       (CFLAGS-vismain.c): New.

Here is the updated patch.  OK for master?

Thanks.


-- 
H.J.
From 4a8b140bf71a22571525e856352a34b61a6c5f18 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Fri, 27 Feb 2015 13:56:44 -0800
Subject: [PATCH] Compile vismain with -fPIE and link with -pie

Protocted symbol in shared library can only be accessed from PIE
or shared library.  Linker in binutils 2.26 enforces it.  We must
compile vismain with -fPIE and link it with -pie.

	[BZ #17711]
	* elf/Makefile (tests): Add vismain only if PIE is enabled.
	(tests-pie): Add vismain.
	(CFLAGS-vismain.c): New.
	* elf/vismain.c: Add comments for PIE requirement.
---
 elf/Makefile  | 5 ++++-
 elf/vismain.c | 5 +++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/elf/Makefile b/elf/Makefile
index f78642e..20b1682 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -130,7 +130,7 @@ endif
 tests += $(tests-static)
 ifeq (yes,$(build-shared))
 tests += loadtest restest1 preloadtest loadfail multiload origtest resolvfail \
-	 constload1 order vismain noload filter unload \
+	 constload1 order noload filter unload \
 	 reldep reldep2 reldep3 reldep4 nodelete nodelete2 \
 	 nodlopen nodlopen2 neededtest neededtest2 \
 	 neededtest3 neededtest4 unload2 lateglobal initfirst global \
@@ -218,6 +218,9 @@ ifeq (yesyes,$(have-fpie)$(build-shared))
 modules-names += tst-piemod1
 tests += tst-pie1 tst-pie2
 tests-pie += tst-pie1 tst-pie2
+tests += vismain
+tests-pie += vismain
+CFLAGS-vismain.c = $(PIE-ccflag)
 endif
 modules-execstack-yes = tst-execstack-mod
 extra-test-objs += $(addsuffix .os,$(strip $(modules-names)))
diff --git a/elf/vismain.c b/elf/vismain.c
index dfcaeeb..05b3748 100644
--- a/elf/vismain.c
+++ b/elf/vismain.c
@@ -15,6 +15,11 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+/* This file must be compiled as PIE to avoid copy relocation when
+   accessing protected symbols defined in shared libaries since copy
+   relocation doesn't work with protected symbols and linker in
+   binutils 2.26 enforces this rule.  */
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-- 
1.9.3


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]