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Date: Sun, 14 Jun 2009 02:00:01 -0400
From: Mike Frysinger <vapier@...too.org>
To: Arnd Bergmann <arnd@...db.de>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] asm-generic: uaccess: do not expand args multiple times
While it's debatable whether {get,put}_user() should be called with
arguments that have side effects, macro's should be written safely in the
first place. In this case, a slightly off version of put_user() ended up
causing random userspace corruption and these things aren't trivial to
track down.
While some of these conversions aren't strictly necessary, I think it's
better to do all of them so as to be proactive in people accidently
screwing it up in the future.
Signed-off-by: Mike Frysinger <vapier@...too.org>
---
include/asm-generic/uaccess.h | 49 ++++++++++++++++++++++------------------
1 files changed, 27 insertions(+), 22 deletions(-)
diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index 6d8cab2..cf3cb73 100644
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -143,15 +143,16 @@ static inline __must_check long __copy_to_user(void __user *to,
#define __put_user(x, ptr) \
({ \
__typeof__(*(ptr)) __x = (x); \
+ __typeof__(*(ptr)) *__p = (ptr); \
int __pu_err = -EFAULT; \
- __chk_user_ptr(ptr); \
- switch (sizeof (*(ptr))) { \
+ __chk_user_ptr(__p); \
+ switch (sizeof(*__p)) { \
case 1: \
case 2: \
case 4: \
case 8: \
- __pu_err = __put_user_fn(sizeof (*(ptr)), \
- ptr, &__x); \
+ __pu_err = __put_user_fn(sizeof(*__p), \
+ __p, &__x); \
break; \
default: \
__put_user_bad(); \
@@ -162,9 +163,11 @@ static inline __must_check long __copy_to_user(void __user *to,
#define put_user(x, ptr) \
({ \
+ __typeof__(*(ptr)) _x = (x); \
+ __typeof__(*(ptr)) *_p = (ptr); \
might_sleep(); \
- __access_ok(ptr, sizeof (*ptr)) ? \
- __put_user(x, ptr) : \
+ __access_ok(_p, sizeof(*_p)) ? \
+ __put_user(_x, _p) : \
-EFAULT; \
})
@@ -178,35 +181,36 @@ extern int __put_user_bad(void) __attribute__((noreturn));
#define __get_user(x, ptr) \
({ \
+ __typeof__(*(ptr)) *__p = (ptr); \
int __gu_err = -EFAULT; \
- __chk_user_ptr(ptr); \
- switch (sizeof(*(ptr))) { \
+ __chk_user_ptr(__p); \
+ switch (sizeof(*__p)) { \
case 1: { \
unsigned char __x; \
- __gu_err = __get_user_fn(sizeof (*(ptr)), \
- ptr, &__x); \
- (x) = *(__force __typeof__(*(ptr)) *) &__x; \
+ __gu_err = __get_user_fn(sizeof(*__p), \
+ __p, &__x); \
+ (x) = *(__force __typeof__(*__p) *) &__x; \
break; \
}; \
case 2: { \
unsigned short __x; \
- __gu_err = __get_user_fn(sizeof (*(ptr)), \
- ptr, &__x); \
- (x) = *(__force __typeof__(*(ptr)) *) &__x; \
+ __gu_err = __get_user_fn(sizeof(*__p), \
+ __p, &__x); \
+ (x) = *(__force __typeof__(*__p) *) &__x; \
break; \
}; \
case 4: { \
unsigned int __x; \
- __gu_err = __get_user_fn(sizeof (*(ptr)), \
- ptr, &__x); \
- (x) = *(__force __typeof__(*(ptr)) *) &__x; \
+ __gu_err = __get_user_fn(sizeof(*__p), \
+ __p, &__x); \
+ (x) = *(__force __typeof__(*__p) *) &__x; \
break; \
}; \
case 8: { \
unsigned long long __x; \
- __gu_err = __get_user_fn(sizeof (*(ptr)), \
- ptr, &__x); \
- (x) = *(__force __typeof__(*(ptr)) *) &__x; \
+ __gu_err = __get_user_fn(sizeof(*__p), \
+ __p, &__x); \
+ (x) = *(__force __typeof__(*__p) *) &__x; \
break; \
}; \
default: \
@@ -218,9 +222,10 @@ extern int __put_user_bad(void) __attribute__((noreturn));
#define get_user(x, ptr) \
({ \
+ __typeof__(*(ptr)) *_p = (ptr); \
might_sleep(); \
- __access_ok(ptr, sizeof (*ptr)) ? \
- __get_user(x, ptr) : \
+ __access_ok(_p, sizeof(*_p)) ? \
+ __get_user(x, _p) : \
-EFAULT; \
})
--
1.6.3.1
--
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