[PATCH] x86: disable stack-protector for __restore_processor_state()

[PATCH] x86: disable stack-protector for __restore_processor_state()

[Joseph Cihula]

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@intel.com>

--- ../linux.trees.git/arch/x86/power/Makefile	2009-03-29 
12:12:13.000000000 -0700
+++ arch/x86/power/Makefile	2009-03-30 12:21:19.000000000 -0700
@@ -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

Re: [PATCH] x86: disable stack-protector for __restore_processor_state()

[Ingo Molnar]

* Joseph Cihula <joseph.cihula@intel.com> wrote:

> 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@intel.com>

ah ... very nice!

applied to tip:x86/urgent, thanks Joseph!

	Ingo

[tip:x86/urgent] x86: disable stack-protector for __restore_processor_state()

[Joseph Cihula]

Commit-ID:  1f23b77e09be10edb30eb03c1b03879083e3cc72
Gitweb:     http://git.kernel.org/tip/1f23b77e09be10edb30eb03c1b03879083e3cc72
Author:     Joseph Cihula <joseph.cihula@intel.com>
AuthorDate: Mon, 30 Mar 2009 14:03:01 -0700
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 3 Apr 2009 19:30:23 +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@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Tejun Heo <tj@kernel.org>
LKML-Reference: <49D13385.5060900@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.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

[tip:x86/urgent] x86: disable stack-protector for __restore_processor_state()

[Joseph Cihula]

Commit-ID:  9b7b89efa3bdaceaa2efb93e2d635391835da209
Gitweb:     http://git.kernel.org/tip/9b7b89efa3bdaceaa2efb93e2d635391835da209
Author:     Joseph Cihula <joseph.cihula@intel.com>
AuthorDate: Mon, 30 Mar 2009 14:03:01 -0700
Committer:  Ingo Molnar <mingo@elte.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@intel.com>
Tested-by: Chris Wright <chrisw@sous-sol.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Tejun Heo <tj@kernel.org>
LKML-Reference: <49D13385.5060900@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.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