Re: [PATCH v2 6/6] openrisc: uaccess: Add user address space check to access_ok

Luc Van Oostenryck
2020-08-06T19:02:35Z

On Thu, Aug 06, 2020 at 06:07:25AM +0900, Stafford Horne wrote:
> Now that __user annotations are fixed for openrisc uaccess api's we can
> add checking to the access_ok macro. This patch adds the __chk_user_ptr
> check, on normal builds the added check is a nop.
>
> Signed-off-by: Stafford Horne <shorne@gmail.com>
> ---
> arch/openrisc/include/asm/uaccess.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/openrisc/include/asm/uaccess.h b/arch/openrisc/include/asm/uaccess.h
> index 85a55359b244..53ddc66abb3f 100644
> --- a/arch/openrisc/include/asm/uaccess.h
> +++ b/arch/openrisc/include/asm/uaccess.h
> @@ -57,7 +57,8 @@ static inline int __range_ok(unsigned long addr, unsigned long size)
>
> #define access_ok(addr, size) \
> ({ \
> - __range_ok((unsigned long)(addr), (size)); \
> + __chk_user_ptr(addr); \
> + __range_ok((__force unsigned long)(addr), (size)); \
> })

Just for info, __force is not needed when casting a pointer to
unsigned long (or uintptr_t). It's not incorrect to use one
but I think it's to avoid __force as much as possible.

-- Luc