powerpc: Use barrier_nospec in copy_from_user()

Based on the x86 commit doing the same.

See commit 304ec1b05031 ("x86/uaccess: Use __uaccess_begin_nospec()
and uaccess_try_nospec") and b3bbfb3fb5d2 ("x86: Introduce
__uaccess_begin_nospec() and uaccess_try_nospec") for more detail.

In all cases we are ordering the load from the potentially
user-controlled pointer vs a previous branch based on an access_ok()
check or similar.

Base on a patch from Michal Suchanek.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index abba80f8ff04a2b621bc86e4a7f18a3a7a20a8e6..468653ce844ce094b3cea1c7f44a55f4fce22a49 100644 (file)
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -258,6 +258,7 @@ do {                                                                \
        __chk_user_ptr(ptr);                                    \
        if (!is_kernel_addr((unsigned long)__gu_addr))          \
                might_fault();                                  \
+       barrier_nospec();                                       \
        __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
        (x) = (__typeof__(*(ptr)))__gu_val;                     \
        __gu_err;                                               \
@@ -269,8 +270,10 @@ do {                                                               \
        unsigned long  __gu_val = 0;                                    \
        const __typeof__(*(ptr)) __user *__gu_addr = (ptr);             \
        might_fault();                                                  \
-       if (access_ok(VERIFY_READ, __gu_addr, (size)))                  \
+       if (access_ok(VERIFY_READ, __gu_addr, (size))) {                \
+               barrier_nospec();                                       \
                __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
+       }                                                               \
        (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
        __gu_err;                                                       \
 })
@@ -281,6 +284,7 @@ do {                                                                \
        unsigned long __gu_val;                                 \
        const __typeof__(*(ptr)) __user *__gu_addr = (ptr);     \
        __chk_user_ptr(ptr);                                    \
+       barrier_nospec();                                       \
        __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
        (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
        __gu_err;                                               \
@@ -308,15 +312,19 @@ static inline unsigned long raw_copy_from_user(void *to,
 
                switch (n) {
                case 1:
+                       barrier_nospec();
                        __get_user_size(*(u8 *)to, from, 1, ret);
                        break;
                case 2:
+                       barrier_nospec();
                        __get_user_size(*(u16 *)to, from, 2, ret);
                        break;
                case 4:
+                       barrier_nospec();
                        __get_user_size(*(u32 *)to, from, 4, ret);
                        break;
                case 8:
+                       barrier_nospec();
                        __get_user_size(*(u64 *)to, from, 8, ret);
                        break;
                }
@@ -324,6 +332,7 @@ static inline unsigned long raw_copy_from_user(void *to,
                        return 0;
        }
 
+       barrier_nospec();
        return __copy_tofrom_user((__force void __user *)to, from, n);
 }