2020-05-28 20:28:03

by Luc Van Oostenryck

Subject: [PATCH 2/2] m68k,nommu: fix implicit cast from __user in __{get,put}_user_asm()

The assembly for __get_user_asm() & __put_user_asm() uses memcpy()
when the size is 8.

However, the pointer is always a __user one while memcpy() expect
a plan one and so this cast creates a lot of warnings when using
Sparse.

So, fix this by adding a cast to 'void __force *' at memcpy()'s
argument.

Reported-by: kbuild test robot <[email protected]>
Signed-off-by: Luc Van Oostenryck <[email protected]>
---
arch/m68k/include/asm/uaccess_no.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/m68k/include/asm/uaccess_no.h b/arch/m68k/include/asm/uaccess_no.h
index 9651766a62af..f32f08a64eaa 100644
--- a/arch/m68k/include/asm/uaccess_no.h
+++ b/arch/m68k/include/asm/uaccess_no.h
@@ -42,7 +42,7 @@ static inline int _access_ok(unsigned long addr, unsigned long size)
__put_user_asm(__pu_err, __pu_val, ptr, l); \
break; \
case 8: \
- memcpy(ptr, &__pu_val, sizeof (*(ptr))); \
+ memcpy((void __force*)ptr, &__pu_val, sizeof (*(ptr))); \
break; \
default: \
__pu_err = __put_user_bad(); \
@@ -85,7 +85,7 @@ extern int __put_user_bad(void);
u64 l; \
__typeof__(*(ptr)) t; \
} __gu_val; \
- memcpy(&__gu_val.l, ptr, sizeof(__gu_val.l)); \
+ memcpy(&__gu_val.l, (const void __force*)ptr, sizeof(__gu_val.l)); \
(x) = __gu_val.t; \
break; \
} \
--
2.26.2

2020-05-29 13:26:40

by Greg Ungerer

Subject: Re: [PATCH 2/2] m68k,nommu: fix implicit cast from __user in __{get,put}_user_asm()

Hi Luc,

On 29/5/20 6:25 am, Luc Van Oostenryck wrote:
> The assembly for __get_user_asm() & __put_user_asm() uses memcpy()
> when the size is 8.
>
> However, the pointer is always a __user one while memcpy() expect
> a plan one and so this cast creates a lot of warnings when using ^^^^
Did you mean "plain"?


> Sparse.
>
> So, fix this by adding a cast to 'void __force *' at memcpy()'s
> argument.
>
> Reported-by: kbuild test robot <[email protected]>
> Signed-off-by: Luc Van Oostenryck <[email protected]>
> ---
> arch/m68k/include/asm/uaccess_no.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/m68k/include/asm/uaccess_no.h b/arch/m68k/include/asm/uaccess_no.h
> index 9651766a62af..f32f08a64eaa 100644
> --- a/arch/m68k/include/asm/uaccess_no.h
> +++ b/arch/m68k/include/asm/uaccess_no.h
> @@ -42,7 +42,7 @@ static inline int _access_ok(unsigned long addr, unsigned long size)
> __put_user_asm(__pu_err, __pu_val, ptr, l); \
> break; \
> case 8: \
> - memcpy(ptr, &__pu_val, sizeof (*(ptr))); \
> + memcpy((void __force*)ptr, &__pu_val, sizeof (*(ptr))); \
^^^
checkpatch wants a ' ' space in there.

Otherwise I think it looks good.

Regards
Greg


> break; \
> default: \
> __pu_err = __put_user_bad(); \
> @@ -85,7 +85,7 @@ extern int __put_user_bad(void);
> u64 l; \
> __typeof__(*(ptr)) t; \
> } __gu_val; \
> - memcpy(&__gu_val.l, ptr, sizeof(__gu_val.l)); \
> + memcpy(&__gu_val.l, (const void __force*)ptr, sizeof(__gu_val.l)); \
> (x) = __gu_val.t; \
> break; \
> } \
>