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Subject[PATCH 4.4 042/266] powerpc: Use barrier_nospec in copy_from_user()
Date
From: Michael Ellerman <mpe@ellerman.id.au>

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/powerpc/include/asm/uaccess.h | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)

--- 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; \
@@ -283,6 +284,7 @@ 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) = (__force __typeof__(*(ptr)))__gu_val; \
__gu_err; \
@@ -295,8 +297,10 @@ 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; \
})
@@ -307,6 +311,7 @@ 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; \
@@ -323,8 +328,10 @@ extern unsigned long __copy_tofrom_user(
static inline unsigned long copy_from_user(void *to,
const void __user *from, unsigned long n)
{
- if (likely(access_ok(VERIFY_READ, from, n)))
+ if (likely(access_ok(VERIFY_READ, from, n))) {
+ barrier_nospec();
return __copy_tofrom_user((__force void __user *)to, from, n);
+ }
memset(to, 0, n);
return n;
}
@@ -359,21 +366,27 @@ static inline unsigned long __copy_from_

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;
}
if (ret == 0)
return 0;
}
+
+ barrier_nospec();
return __copy_tofrom_user((__force void __user *)to, from, n);
}

@@ -400,6 +413,7 @@ static inline unsigned long __copy_to_us
if (ret == 0)
return 0;
}
+
return __copy_tofrom_user(to, (__force const void __user *)from, n);
}


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