2008-03-02 23:23:24

by Al Viro

Subject: [RFC] breakage in 4223cc34365e4 (h8300: uaccess.h update)

After that commit in asm-h8300/uaccess.h we have

#define get_user(x, ptr) \
({ \
int __gu_err = 0; \
uint32_t __gu_val = 0; \
^^^^^^^^^^^^^^^^^
switch (sizeof(*(ptr))) { \
case 1: \
case 2: \
case 4: \
__gu_val = *(ptr); \
break; \
case 8: \
memcpy(&__gu_val, ptr, sizeof (*(ptr))); \
^^^^^^^^^^^^^^^^

which, of course, is FUBAR whenever we actually hit that case - memcpy of
8 bytes into uint32_t is obviously wrong. Why don't we simply do

#define get_user(x, ptr) \
({ \
int __gu_err = 0; \
typeof(*(ptr)) __gu_val = *ptr; \
switch (sizeof(*(ptr))) { \
case 1: \
case 2: \
case 4: \
case 8: \
break; \
default: \
__gu_err = __get_user_bad(); \
break; \
} \
(x) = __gu_val; \
__gu_err; \
})

and be done with that, anyway?

2008-03-10 20:57:17

by Yoshinori Sato

Subject: Re: [RFC] breakage in 4223cc34365e4 (h8300: uaccess.h update)

At Sun, 2 Mar 2008 23:23:14 +0000,
Al Viro wrote:
>
> After that commit in asm-h8300/uaccess.h we have
>
> #define get_user(x, ptr) \
> ({ \
> int __gu_err = 0; \
> uint32_t __gu_val = 0; \
> ^^^^^^^^^^^^^^^^^
> switch (sizeof(*(ptr))) { \
> case 1: \
> case 2: \
> case 4: \
> __gu_val = *(ptr); \
> break; \
> case 8: \
> memcpy(&__gu_val, ptr, sizeof (*(ptr))); \
> ^^^^^^^^^^^^^^^^
>
> which, of course, is FUBAR whenever we actually hit that case - memcpy of
> 8 bytes into uint32_t is obviously wrong. Why don't we simply do

Oops.

>
> #define get_user(x, ptr) \
> ({ \
> int __gu_err = 0; \
> typeof(*(ptr)) __gu_val = *ptr; \
> switch (sizeof(*(ptr))) { \
> case 1: \
> case 2: \
> case 4: \
> case 8: \
> break; \
> default: \
> __gu_err = __get_user_bad(); \
> break; \
> } \
> (x) = __gu_val; \
> __gu_err; \
> })
>
> and be done with that, anyway?

Good! no problem.
Thank you.

Signed-off-by: Al Viro <[email protected]>
Signed-off-by: Yoshinori Sato <[email protected]>

include/asm-h8300/uaccess.h | 11 ++++-------
1 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/include/asm-h8300/uaccess.h b/include/asm-h8300/uaccess.h
index a22350e..356068c 100644
--- a/include/asm-h8300/uaccess.h
+++ b/include/asm-h8300/uaccess.h
@@ -91,22 +91,19 @@ extern int __put_user_bad(void);
#define get_user(x, ptr) \
({ \
int __gu_err = 0; \
- uint32_t __gu_val = 0; \
+ typeof(*(ptr)) __gu_val = *ptr; \
switch (sizeof(*(ptr))) { \
case 1: \
case 2: \
case 4: \
- __gu_val = *(ptr); \
- break; \
- case 8: \
- memcpy(&__gu_val, ptr, sizeof (*(ptr))); \
+ case 8: \
break; \
default: \
- __gu_val = 0; \
__gu_err = __get_user_bad(); \
+ __gu_val = 0; \
break; \
} \
- (x) = (typeof(*(ptr)))__gu_val; \
+ (x) = __gu_val; \
__gu_err; \
})
#define __get_user(x, ptr) get_user(x, ptr)
--
1.5.4.3

--
Yoshinori Sato
<[email protected]>