ARM: 7527/1: uaccess: explicitly check __user pointer when !CPU_USE_DOMAINS

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>
Cc: stable@vger.kernel.org
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

4 files changed, 56 insertions, 21 deletions

diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 03fb93621d0d..5c8b3bf4d825 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -320,4 +320,12 @@
         .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__ */
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 479a6352e0b5..6f83ad6e4d3d 100644
--- 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 int);
 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;                 \
                 }                                                       \
diff --git a/arch/arm/lib/getuser.S b/arch/arm/lib/getuser.S
index 11093a7c3e32..9b06bb41fca6 100644
--- 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: TUSER(ldrb)  r2, [r0]
         mov     r0, #0
         mov     pc, lr
 ENDPROC(__get_user_1)
 
 ENTRY(__get_user_2)
-#ifdef CONFIG_THUMB2_KERNEL
-2: TUSER(ldrb)  r2, [r0]
-3: TUSER(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: TUSER(ldrb)  r2, [r0], #1
-3: TUSER(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: TUSER(ldr)   r2, [r0]
         mov     r0, #0
         mov     pc, lr
diff --git a/arch/arm/lib/putuser.S b/arch/arm/lib/putuser.S
index 7db25990c589..3d73dcb959b0 100644
--- 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: TUSER(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: TUSER(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: TUSER(str)   r2, [r0]
 6: TUSER(str)   r3, [r0, #4]