Re: [PATCH v2 02/18] uaccess: fix nios2 and microblaze get_user_8()

Dinh Nguyen
2022-02-25T04:28:32Z

On 2/16/22 07:13, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> These two architectures implement 8-byte get_user() through
> a memcpy() into a four-byte variable, which won't fit.
>
> Use a temporary 64-bit variable instead here, and use a double
> cast the way that risc-v and openrisc do to avoid compile-time
> warnings.
>
> Fixes: 6a090e97972d ("arch/microblaze: support get_user() of size 8 bytes")
> Fixes: 5ccc6af5e88e ("nios2: Memory management")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> arch/microblaze/include/asm/uaccess.h | 18 +++++++++---------
> arch/nios2/include/asm/uaccess.h | 26 ++++++++++++++++----------
> 2 files changed, 25 insertions(+), 19 deletions(-)
>
> diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
> index 5b6e0e7788f4..3fe96979d2c6 100644
> --- a/arch/microblaze/include/asm/uaccess.h
> +++ b/arch/microblaze/include/asm/uaccess.h
> @@ -130,27 +130,27 @@ extern long __user_bad(void);
>
> #define __get_user(x, ptr) \
> ({ \
> - unsigned long __gu_val = 0; \
> long __gu_err; \
> switch (sizeof(*(ptr))) { \
> case 1: \
> - __get_user_asm("lbu", (ptr), __gu_val, __gu_err); \
> + __get_user_asm("lbu", (ptr), x, __gu_err); \
> break; \
> case 2: \
> - __get_user_asm("lhu", (ptr), __gu_val, __gu_err); \
> + __get_user_asm("lhu", (ptr), x, __gu_err); \
> break; \
> case 4: \
> - __get_user_asm("lw", (ptr), __gu_val, __gu_err); \
> + __get_user_asm("lw", (ptr), x, __gu_err); \
> break; \
> - case 8: \
> - __gu_err = __copy_from_user(&__gu_val, ptr, 8); \
> - if (__gu_err) \
> - __gu_err = -EFAULT; \
> + case 8: { \
> + __u64 __x = 0; \
> + __gu_err = raw_copy_from_user(&__x, ptr, 8) ? \
> + -EFAULT : 0; \
> + (x) = (typeof(x))(typeof((x) - (x)))__x; \
> break; \
> + } \
> default: \
> /* __gu_val = 0; __gu_err = -EINVAL;*/ __gu_err = __user_bad();\
> } \
> - x = (__force __typeof__(*(ptr))) __gu_val; \
> __gu_err; \
> })
>
> diff --git a/arch/nios2/include/asm/uaccess.h b/arch/nios2/include/asm/uaccess.h
> index ba9340e96fd4..ca9285a915ef 100644
> --- a/arch/nios2/include/asm/uaccess.h
> +++ b/arch/nios2/include/asm/uaccess.h
> @@ -88,6 +88,7 @@ extern __must_check long strnlen_user(const char __user *s, long n);
> /* Optimized macros */
> #define __get_user_asm(val, insn, addr, err) \
> { \
> + unsigned long __gu_val; \
> __asm__ __volatile__( \
> " movi %0, %3\n" \
> "1: " insn " %1, 0(%2)\n" \
> @@ -96,14 +97,20 @@ extern __must_check long strnlen_user(const char __user *s, long n);
> " .section __ex_table,\"a\"\n" \
> " .word 1b, 2b\n" \
> " .previous" \
> - : "=&r" (err), "=r" (val) \
> + : "=&r" (err), "=r" (__gu_val) \
> : "r" (addr), "i" (-EFAULT)); \
> + val = (__force __typeof__(*(addr)))__gu_val; \
> }
>
> -#define __get_user_unknown(val, size, ptr, err) do { \
> +extern void __get_user_unknown(void);
> +
> +#define __get_user_8(val, ptr, err) do { \
> + u64 __val = 0; \
> err = 0; \
> - if (__copy_from_user(&(val), ptr, size)) { \
> + if (raw_copy_from_user(&(__val), ptr, sizeof(val))) { \
> err = -EFAULT; \
> + } else { \
> + val = (typeof(val))(typeof((val) - (val)))__val; \
> } \
> } while (0)
>
> @@ -119,8 +126,11 @@ do { \
> case 4: \
> __get_user_asm(val, "ldw", ptr, err); \
> break; \
> + case 8: \
> + __get_user_8(val, ptr, err); \
> + break; \
> default: \
> - __get_user_unknown(val, size, ptr, err); \
> + __get_user_unknown(); \
> break; \
> } \
> } while (0)
> @@ -129,9 +139,7 @@ do { \
> ({ \
> long __gu_err = -EFAULT; \
> const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \
> - unsigned long __gu_val = 0; \
> - __get_user_common(__gu_val, sizeof(*(ptr)), __gu_ptr, __gu_err);\
> - (x) = (__force __typeof__(x))__gu_val; \
> + __get_user_common(x, sizeof(*(ptr)), __gu_ptr, __gu_err); \
> __gu_err; \
> })
>
> @@ -139,11 +147,9 @@ do { \
> ({ \
> long __gu_err = -EFAULT; \
> const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \
> - unsigned long __gu_val = 0; \
> if (access_ok( __gu_ptr, sizeof(*__gu_ptr))) \
> - __get_user_common(__gu_val, sizeof(*__gu_ptr), \
> + __get_user_common(x, sizeof(*__gu_ptr), \
> __gu_ptr, __gu_err); \
> - (x) = (__force __typeof__(x))__gu_val; \
> __gu_err; \
> })
>

Acked-by: Dinh Nguyen <dinguyen@kernel.org>