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Disable stack protector in early static initialization [BZ #7065] 

The startup code in csu/, and the brk and sbrk functions are
needed very early in initialization of a statically-linked program,
before the stack guard is initialized; TLS initialization also uses
memcpy, which cannot overrun its own stack.  Mark all of these as
-fno-stack-protector.

We also finally introduce @libc_cv_ssp@ and @no_stack_protector@, both
substituted by the configury changes made earlier, to detect the case
when -fno-stack-protector is supported by the compiler, and
unconditionally pass it in when this is the case, whether or not
--enable-stack-protector is passed to configure.  (This means that
it'll even work when the compiler's been hacked to pass
-fstack-protector by default, unless the hackage is so broken that
it does so in a way that is impossible to override.)
This commit is contained in:
Nick Alcock 2016-12-26 10:08:45 +01:00 committed by Florian Weimer
parent de6591238b
commit 10c85e76c0
5 changed files with 29 additions and 0 deletions
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12
ChangeLog
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@ -1,3 +1,15 @@
2016-12-26 Nick Alcock <nick.alcock@oracle.com>
[BZ #7065]
* config.make.in (have-ssp, no-stack-protector): New.
* csu/Makefile (CFLAGS-.o, CFLAGS-.op, CFLAGS-.os): Use it.
* misc/Makefile (CFLAGS-sbrk.o): Likewise.
(CFLAGS-sbrk.op): Likewise.
(CFLAGS-brk.o): Likewise.
(CFLAGS-brk.op): Likewise.
* string/Makefile (CFLAGS-memcpy.c): Likewise.
(CFLAGS-wordcopy.c): Likewise.
2016-12-26 Nick Alcock <nick.alcock@oracle.com>
[BZ #7065]

2
config.make.in
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@ -58,7 +58,9 @@ with-fp = @with_fp@
enable-timezone-tools = @enable_timezone_tools@
unwind-find-fde = @libc_cv_gcc_unwind_find_fde@
have-fpie = @libc_cv_fpie@
have-ssp = @libc_cv_ssp@
stack-protector = @stack_protector@
no-stack-protector = @no_stack_protector@
have-selinux = @have_selinux@
have-libaudit = @have_libaudit@
have-libcap = @have_libcap@

4
csu/Makefile
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@ -46,6 +46,10 @@ before-compile += $(objpfx)version-info.h
# code is compiled with special flags.
tests =
CFLAGS-.o += $(no-stack-protector)
CFLAGS-.op += $(no-stack-protector)
CFLAGS-.os += $(no-stack-protector)
ifeq (yes,$(build-shared))
extra-objs += S$(start-installed-name) gmon-start.os
ifneq ($(start-installed-name),$(static-start-installed-name))

7
misc/Makefile
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@ -108,6 +108,13 @@ CFLAGS-getusershell.c = -fexceptions
CFLAGS-err.c = -fexceptions
CFLAGS-tst-tsearch.c = $(stack-align-test-flags)
# Called during static library initialization, so turn stack-protection
# off for non-shared builds.
CFLAGS-sbrk.o = $(no-stack-protector)
CFLAGS-sbrk.op = $(no-stack-protector)
CFLAGS-brk.o = $(no-stack-protector)
CFLAGS-brk.op = $(no-stack-protector)
include ../Rules
$(objpfx)libg.a: $(dep-dummy-lib); $(make-dummy-lib)

4
string/Makefile
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@ -73,6 +73,10 @@ CFLAGS-test-ffs.c = -fno-builtin
CFLAGS-tst-inlcall.c = -fno-builtin
CFLAGS-tst-xbzero-opt.c = -O3
# Called during TLS initialization.
CFLAGS-memcpy.c = $(no-stack-protector)
CFLAGS-wordcopy.c = $(no-stack-protector)
ifeq ($(run-built-tests),yes)
$(objpfx)tst-svc-cmp.out: tst-svc.expect $(objpfx)tst-svc.out
cmp $^ > $@; \