[PATCH stable v4.9 07/35] powerpc: Use barrier_nospec in copy_from_user()

Michael Ellerman
2019-04-11T11:46:45Z

commit ddf35cf3764b5a182b178105f57515b42e2634f8 upstream.

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>
---
arch/powerpc/include/asm/uaccess.h | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 31913b3ac7ab..da852153c1f8 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -269,6 +269,7 @@ 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; \
@@ -280,8 +281,10 @@ do { \
unsigned long __gu_val = 0; \
__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; \
})
@@ -292,6 +295,7 @@ do { \
unsigned long __gu_val; \
__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; \
@@ -348,15 +352,19 @@ static inline unsigned long __copy_from_user_inatomic(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;
}
@@ -366,6 +374,7 @@ static inline unsigned long __copy_from_user_inatomic(void *to,

check_object_size(to, n, false);

+ barrier_nospec();
return __copy_tofrom_user((__force void __user *)to, from, n);
}

--
2.20.1