[ 3.5.y.z extended stable ] Patch "ARM: poison memory between kuser helpers" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ARM: poison memory between kuser helpers

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 3d8c47cc47406b8f3568fd156c66a59a3dec12ba Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel at arm.linux.org.uk>
Date: Thu, 4 Jul 2013 11:32:04 +0100
Subject: [PATCH] ARM: poison memory between kuser helpers

commit 5b43e7a383d69381ffe53423e46dd0fafae07da3 upstream.

Poison the memory between each kuser helper.  This ensures that any
branch between the kuser helpers will be appropriately trapped.

Acked-by: Nicolas Pitre <nico at linaro.org>
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/arm/kernel/entry-armv.S | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 0f82098..9c80c1d 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -784,6 +784,17 @@ ENDPROC(__switch_to)
 #endif
 	.endm

+	.macro	kuser_pad, sym, size
+	.if	(. - \sym) & 3
+	.rept	4 - (. - \sym) & 3
+	.byte	0
+	.endr
+	.endif
+	.rept	(\size - (. - \sym)) / 4
+	.word	0xe7fddef1
+	.endr
+	.endm
+
 	.align	5
 	.globl	__kuser_helper_start
 __kuser_helper_start:
@@ -874,18 +885,13 @@ kuser_cmpxchg64_fixup:
 #error "incoherent kernel configuration"
 #endif

-	/* pad to next slot */
-	.rept	(16 - (. - __kuser_cmpxchg64)/4)
-	.word	0
-	.endr
-
-	.align	5
+	kuser_pad __kuser_cmpxchg64, 64

 __kuser_memory_barrier:				@ 0xffff0fa0
 	smp_dmb	arm
 	usr_ret	lr

-	.align	5
+	kuser_pad __kuser_memory_barrier, 32

 __kuser_cmpxchg:				@ 0xffff0fc0

@@ -958,13 +964,14 @@ kuser_cmpxchg32_fixup:

 #endif

-	.align	5
+	kuser_pad __kuser_cmpxchg, 32

 __kuser_get_tls:				@ 0xffff0fe0
 	ldr	r0, [pc, #(16 - 8)]	@ read TLS, set in kuser_get_tls_init
 	usr_ret	lr
 	mrc	p15, 0, r0, c13, c0, 3	@ 0xffff0fe8 hardware TLS code
-	.rep	4
+	kuser_pad __kuser_get_tls, 16
+	.rep	3
 	.word	0			@ 0xffff0ff0 software TLS value, then
 	.endr				@ pad up to __kuser_helper_version

--
1.8.3.2