[PATCH 3.2 176/185] ARM: 7527/1: uaccess: explicitly check __user pointer when !CPU_USE_DOMAINS

Ben Hutchings
2013-12-29T02:08:44Z

From: Russell King <rmk+kernel@arm.linux.org.uk>

commit 8404663f81d212918ff85f493649a7991209fa04 upstream.

The {get,put}_user macros don't perform range checking on the provided
__user address when !CPU_HAS_DOMAINS.

This patch reworks the out-of-line assembly accessors to check the user
address against a specified limit, returning -EFAULT if is is out of
range.

[will: changed get_user register allocation to match put_user]
[rmk: fixed building on older ARM architectures]

Reported-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[bwh: Backported to 3.2: TUSER() was called T()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/arm/include/asm/assembler.h | 8 ++++++++
arch/arm/include/asm/uaccess.h | 40 +++++++++++++++++++++++++++-------------
arch/arm/lib/getuser.S | 23 +++++++++++++++--------
arch/arm/lib/putuser.S | 6 ++++++
4 files changed, 56 insertions(+), 21 deletions(-)

--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -307,4 +307,12 @@
.size \name , . - \name
.endm

+ .macro check_uaccess, addr:req, size:req, limit:req, tmp:req, bad:req
+#ifndef CONFIG_CPU_USE_DOMAINS
+ adds \tmp, \addr, #\size - 1
+ sbcccs \tmp, \tmp, \limit
+ bcs \bad
+#endif
+ .endm
+
#endif /* __ASM_ASSEMBLER_H__ */
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -101,28 +101,39 @@ extern int __get_user_1(void *);
extern int __get_user_2(void *);
extern int __get_user_4(void *);

-#define __get_user_x(__r2,__p,__e,__s,__i...) \
+#define __GUP_CLOBBER_1 "lr", "cc"
+#ifdef CONFIG_CPU_USE_DOMAINS
+#define __GUP_CLOBBER_2 "ip", "lr", "cc"
+#else
+#define __GUP_CLOBBER_2 "lr", "cc"
+#endif
+#define __GUP_CLOBBER_4 "lr", "cc"
+
+#define __get_user_x(__r2,__p,__e,__l,__s) \
__asm__ __volatile__ ( \
__asmeq("%0", "r0") __asmeq("%1", "r2") \
+ __asmeq("%3", "r1") \
"bl __get_user_" #__s \
: "=&r" (__e), "=r" (__r2) \
- : "0" (__p) \
- : __i, "cc")
+ : "0" (__p), "r" (__l) \
+ : __GUP_CLOBBER_##__s)

#define get_user(x,p) \
({ \
+ unsigned long __limit = current_thread_info()->addr_limit - 1; \
register const typeof(*(p)) __user *__p asm("r0") = (p);\
register unsigned long __r2 asm("r2"); \
+ register unsigned long __l asm("r1") = __limit; \
register int __e asm("r0"); \
switch (sizeof(*(__p))) { \
case 1: \
- __get_user_x(__r2, __p, __e, 1, "lr"); \
- break; \
+ __get_user_x(__r2, __p, __e, __l, 1); \
+ break; \
case 2: \
- __get_user_x(__r2, __p, __e, 2, "r3", "lr"); \
+ __get_user_x(__r2, __p, __e, __l, 2); \
break; \
case 4: \
- __get_user_x(__r2, __p, __e, 4, "lr"); \
+ __get_user_x(__r2, __p, __e, __l, 4); \
break; \
default: __e = __get_user_bad(); break; \
} \
@@ -135,31 +146,34 @@ extern int __put_user_2(void *, unsigned
extern int __put_user_4(void *, unsigned int);
extern int __put_user_8(void *, unsigned long long);

-#define __put_user_x(__r2,__p,__e,__s) \
+#define __put_user_x(__r2,__p,__e,__l,__s) \
__asm__ __volatile__ ( \
__asmeq("%0", "r0") __asmeq("%2", "r2") \
+ __asmeq("%3", "r1") \
"bl __put_user_" #__s \
: "=&r" (__e) \
- : "0" (__p), "r" (__r2) \
+ : "0" (__p), "r" (__r2), "r" (__l) \
: "ip", "lr", "cc")

#define put_user(x,p) \
({ \
+ unsigned long __limit = current_thread_info()->addr_limit - 1; \
register const typeof(*(p)) __r2 asm("r2") = (x); \
register const typeof(*(p)) __user *__p asm("r0") = (p);\
+ register unsigned long __l asm("r1") = __limit; \
register int __e asm("r0"); \
switch (sizeof(*(__p))) { \
case 1: \
- __put_user_x(__r2, __p, __e, 1); \
+ __put_user_x(__r2, __p, __e, __l, 1); \
break; \
case 2: \
- __put_user_x(__r2, __p, __e, 2); \
+ __put_user_x(__r2, __p, __e, __l, 2); \
break; \
case 4: \
- __put_user_x(__r2, __p, __e, 4); \
+ __put_user_x(__r2, __p, __e, __l, 4); \
break; \
case 8: \
- __put_user_x(__r2, __p, __e, 8); \
+ __put_user_x(__r2, __p, __e, __l, 8); \
break; \
default: __e = __put_user_bad(); break; \
} \
--- a/arch/arm/lib/getuser.S
+++ b/arch/arm/lib/getuser.S
@@ -16,8 +16,9 @@
* __get_user_X
*
* Inputs: r0 contains the address
+ * r1 contains the address limit, which must be preserved
* Outputs: r0 is the error code
- * r2, r3 contains the zero-extended value
+ * r2 contains the zero-extended value
* lr corrupted
*
* No other registers must be altered. (see <asm/uaccess.h>
@@ -27,33 +28,39 @@
* Note also that it is intended that __get_user_bad is not global.
*/
#include <linux/linkage.h>
+#include <asm/assembler.h>
#include <asm/errno.h>
#include <asm/domain.h>

ENTRY(__get_user_1)
+ check_uaccess r0, 1, r1, r2, __get_user_bad
1: T(ldrb) r2, [r0]
mov r0, #0
mov pc, lr
ENDPROC(__get_user_1)

ENTRY(__get_user_2)
-#ifdef CONFIG_THUMB2_KERNEL
-2: T(ldrb) r2, [r0]
-3: T(ldrb) r3, [r0, #1]
+ check_uaccess r0, 2, r1, r2, __get_user_bad
+#ifdef CONFIG_CPU_USE_DOMAINS
+rb .req ip
+2: ldrbt r2, [r0], #1
+3: ldrbt rb, [r0], #0
#else
-2: T(ldrb) r2, [r0], #1
-3: T(ldrb) r3, [r0]
+rb .req r0
+2: ldrb r2, [r0]
+3: ldrb rb, [r0, #1]
#endif
#ifndef __ARMEB__
- orr r2, r2, r3, lsl #8
+ orr r2, r2, rb, lsl #8
#else
- orr r2, r3, r2, lsl #8
+ orr r2, rb, r2, lsl #8
#endif
mov r0, #0
mov pc, lr
ENDPROC(__get_user_2)

ENTRY(__get_user_4)
+ check_uaccess r0, 4, r1, r2, __get_user_bad
4: T(ldr) r2, [r0]
mov r0, #0
mov pc, lr
--- a/arch/arm/lib/putuser.S
+++ b/arch/arm/lib/putuser.S
@@ -16,6 +16,7 @@
* __put_user_X
*
* Inputs: r0 contains the address
+ * r1 contains the address limit, which must be preserved
* r2, r3 contains the value
* Outputs: r0 is the error code
* lr corrupted
@@ -27,16 +28,19 @@
* Note also that it is intended that __put_user_bad is not global.
*/
#include <linux/linkage.h>
+#include <asm/assembler.h>
#include <asm/errno.h>
#include <asm/domain.h>

ENTRY(__put_user_1)
+ check_uaccess r0, 1, r1, ip, __put_user_bad
1: T(strb) r2, [r0]
mov r0, #0
mov pc, lr
ENDPROC(__put_user_1)

ENTRY(__put_user_2)
+ check_uaccess r0, 2, r1, ip, __put_user_bad
mov ip, r2, lsr #8
#ifdef CONFIG_THUMB2_KERNEL
#ifndef __ARMEB__
@@ -60,12 +64,14 @@ ENTRY(__put_user_2)
ENDPROC(__put_user_2)

ENTRY(__put_user_4)
+ check_uaccess r0, 4, r1, ip, __put_user_bad
4: T(str) r2, [r0]
mov r0, #0
mov pc, lr
ENDPROC(__put_user_4)

ENTRY(__put_user_8)
+ check_uaccess r0, 8, r1, ip, __put_user_bad
#ifdef CONFIG_THUMB2_KERNEL
5: T(str) r2, [r0]
6: T(str) r3, [r0, #4]