Ignore __stack_chk_fail* in the rtld mapfile computation [BZ #7065]

The previous commit prevented rtld itself from being built with
-fstack-protector, but this is not quite enough.  We identify which
objects belong in rtld via a test link and analysis of the resulting
mapfile.  That link is necessarily done against objects that are
stack-protected, so drags in __stack_chk_fail_local, __stack_chk_fail,
and all the libc and libio code they use.

To stop this happening, use --defsym in the test librtld.map-production
link to force the linker to predefine these two symbols (to 0, but it
could be to anything).  (In a real link, this would of course be
catastrophic, but these object files are never used for anything else.)

1 files changed, 6 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 82fc4e29d3..ae58d91110 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,12 @@
 2016-12-26  Nick Alcock  <nick.alcock@oracle.com>
 
 	[BZ #7065]
+	* elf/Makefile (dummy-stack-chk-fail): New.
+	(librtld.map): Use it.
+
+2016-12-26  Nick Alcock  <nick.alcock@oracle.com>
+
+	[BZ #7065]
 	Compile the dynamic linker without stack protection.
 	* elf/Makefile (elide-stack-protector): New.
 	(CFLAGS-.os): Use it, eliding $(all-rtld-routines).