Patchwork [15/18] Avoid stack-protecting signal-handling functions sibcalled from assembly.

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Submitter Nix
Date March 8, 2016, 1:51 p.m.
Message ID <1457445064-7107-16-git-send-email-nix@esperi.org.uk>
Download mbox | patch
Permalink /patch/11264/
State New
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Comments

Nix - March 8, 2016, 1:51 p.m.
From: Nick Alcock <nick.alcock@oracle.com>

Certain signal-handling functions are sibcalled from assembly on
x86, both on Linux and the Hurd.  As such, they depend on having
the same-shaped stack frame, an assumption it seems likely that
-fstack-protector violates.  More worryingly, setjmp/sigjmp.c lands
in the dynamic linker but is overlooked by the machinery that
rebuilds almost everything else, and is never rebuilt: so we
should compile it witout stack-protection for the sake of ld.so.

v2: de-stack-protect setjmp/sigjmp.c.
v3: Use $(no-stack-protector).
v4: Use inhibit_stack_protector.
v5: Remove inhibition of nptl/pthread_mutex_(un)lock.c now that is
    diagnosed and fixed elsewhere, properly; inhibit _hurd_self_sigstate
    instead.

	* hurd/hurd/signal.h (_hurd_self_sigstate): Add
	inhibit_stack_protector.
	* setjmp/Makefile (CFLAGS-sigjmp.c): Add $(no-stack-protector).
---
 hurd/hurd/signal.h | 2 +-
 setjmp/Makefile    | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

Patch

diff --git a/hurd/hurd/signal.h b/hurd/hurd/signal.h
index 85e5152..78a25ae 100644
--- a/hurd/hurd/signal.h
+++ b/hurd/hurd/signal.h
@@ -129,7 +129,7 @@  extern struct hurd_sigstate *_hurd_self_sigstate (void)
 #define _HURD_SIGNAL_H_EXTERN_INLINE __extern_inline
 #endif
 
-_HURD_SIGNAL_H_EXTERN_INLINE struct hurd_sigstate *
+_HURD_SIGNAL_H_EXTERN_INLINE inhibit_stack_protector struct hurd_sigstate *
 _hurd_self_sigstate (void)
 {
   struct hurd_sigstate **location = (struct hurd_sigstate **)
diff --git a/setjmp/Makefile b/setjmp/Makefile
index 5b677cc..b617a84 100644
--- a/setjmp/Makefile
+++ b/setjmp/Makefile
@@ -35,3 +35,7 @@  tests-static	:= tst-setjmp-static
 include ../Rules
 
 $(objpfx)tst-setjmp-fp: $(libm)
+
+# This is sibcalled directly from arch-specific assembly, included in rtld,
+# but never rebuilt, so it must never be built with stack protection.
+CFLAGS-sigjmp.c += $(no-stack-protector)