linux-kernel - [tip:x86/urgent] x86: disable stack-protector for __restore_processor

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Message-ID: <tip-9b7b89efa3bdaceaa2efb93e2d635391835da209@git.kernel.org>
Date:	Fri, 3 Apr 2009 17:51:36 GMT
From:	Joseph Cihula <joseph.cihula@...el.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	arjan@...ux.intel.com, joseph.cihula@...el.com,
	chrisw@...s-sol.org, tj@...nel.org, tglx@...utronix.de,
	mingo@...e.hu
Subject: [tip:x86/urgent] x86: disable stack-protector for __restore_processor_state()

Commit-ID:  9b7b89efa3bdaceaa2efb93e2d635391835da209
Gitweb:     http://git.kernel.org/tip/9b7b89efa3bdaceaa2efb93e2d635391835da209
Author:     Joseph Cihula <joseph.cihula@...el.com>
AuthorDate: Mon, 30 Mar 2009 14:03:01 -0700
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 3 Apr 2009 19:48:41 +0200

x86: disable stack-protector for __restore_processor_state()

The __restore_processor_state() fn restores %gs on resume from S3.  As
such, it cannot be protected by the stack-protector guard since %gs will
not be correct on function entry.

There are only a few other fns in this file and it should not negatively
impact kernel security that they will also have the stack-protector
guard removed (and so it's not worth moving them to another file).

Without this change, S3 resume on a kernel built with
CONFIG_CC_STACKPROTECTOR_ALL=y will fail.

Signed-off-by: Joseph Cihula <joseph.cihula@...el.com>
Tested-by: Chris Wright <chrisw@...s-sol.org>
Cc: Arjan van de Ven <arjan@...ux.intel.com>
Cc: Tejun Heo <tj@...nel.org>
LKML-Reference: <49D13385.5060900@...el.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 arch/x86/power/Makefile |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/arch/x86/power/Makefile b/arch/x86/power/Makefile
index 9ff4d5b..58b32db 100644
--- a/arch/x86/power/Makefile
+++ b/arch/x86/power/Makefile
@@ -1,2 +1,7 @@
+# __restore_processor_state() restores %gs after S3 resume and so should not
+# itself be stack-protected
+nostackp := $(call cc-option, -fno-stack-protector)
+CFLAGS_cpu_$(BITS).o	:= $(nostackp)
+
 obj-$(CONFIG_PM_SLEEP)		+= cpu_$(BITS).o
 obj-$(CONFIG_HIBERNATION)	+= hibernate_$(BITS).o hibernate_asm_$(BITS).o
--
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