[PATCH 4.14 063/195] [Variant 1/Spectre-v1] arm64: uaccess: Mask __user pointers for __arch_{clear, copy_*}_user

From: Greg Kroah-Hartman
Date: Thu Feb 15 2018 - 12:42:01 EST


4.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Will Deacon <will.deacon@xxxxxxx>


Commit f71c2ffcb20d upstream.

Like we've done for get_user and put_user, ensure that user pointers
are masked before invoking the underlying __arch_{clear,copy_*}_user
operations.

Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/uaccess.h | 29 ++++++++++++++++++++++-------
arch/arm64/kernel/arm64ksyms.c | 4 ++--
arch/arm64/lib/clear_user.S | 6 +++---
arch/arm64/lib/copy_in_user.S | 5 +++--
4 files changed, 30 insertions(+), 14 deletions(-)

--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -391,20 +391,35 @@ do { \
#define put_user __put_user

extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n);
-#define raw_copy_from_user __arch_copy_from_user
+#define raw_copy_from_user(to, from, n) \
+({ \
+ __arch_copy_from_user((to), __uaccess_mask_ptr(from), (n)); \
+})
+
extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n);
-#define raw_copy_to_user __arch_copy_to_user
-extern unsigned long __must_check raw_copy_in_user(void __user *to, const void __user *from, unsigned long n);
-extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
+#define raw_copy_to_user(to, from, n) \
+({ \
+ __arch_copy_to_user(__uaccess_mask_ptr(to), (from), (n)); \
+})
+
+extern unsigned long __must_check __arch_copy_in_user(void __user *to, const void __user *from, unsigned long n);
+#define raw_copy_in_user(to, from, n) \
+({ \
+ __arch_copy_in_user(__uaccess_mask_ptr(to), \
+ __uaccess_mask_ptr(from), (n)); \
+})
+
#define INLINE_COPY_TO_USER
#define INLINE_COPY_FROM_USER

-static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
+extern unsigned long __must_check __arch_clear_user(void __user *to, unsigned long n);
+static inline unsigned long __must_check __clear_user(void __user *to, unsigned long n)
{
if (access_ok(VERIFY_WRITE, to, n))
- n = __clear_user(__uaccess_mask_ptr(to), n);
+ n = __arch_clear_user(__uaccess_mask_ptr(to), n);
return n;
}
+#define clear_user __clear_user

extern long strncpy_from_user(char *dest, const char __user *src, long count);

@@ -418,7 +433,7 @@ extern unsigned long __must_check __copy
static inline int __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size)
{
kasan_check_write(dst, size);
- return __copy_user_flushcache(dst, src, size);
+ return __copy_user_flushcache(dst, __uaccess_mask_ptr(src), size);
}
#endif

--- a/arch/arm64/kernel/arm64ksyms.c
+++ b/arch/arm64/kernel/arm64ksyms.c
@@ -37,8 +37,8 @@ EXPORT_SYMBOL(clear_page);
/* user mem (segment) */
EXPORT_SYMBOL(__arch_copy_from_user);
EXPORT_SYMBOL(__arch_copy_to_user);
-EXPORT_SYMBOL(__clear_user);
-EXPORT_SYMBOL(raw_copy_in_user);
+EXPORT_SYMBOL(__arch_clear_user);
+EXPORT_SYMBOL(__arch_copy_in_user);

/* physical memory */
EXPORT_SYMBOL(memstart_addr);
--- a/arch/arm64/lib/clear_user.S
+++ b/arch/arm64/lib/clear_user.S
@@ -21,7 +21,7 @@

.text

-/* Prototype: int __clear_user(void *addr, size_t sz)
+/* Prototype: int __arch_clear_user(void *addr, size_t sz)
* Purpose : clear some user memory
* Params : addr - user memory address to clear
* : sz - number of bytes to clear
@@ -29,7 +29,7 @@
*
* Alignment fixed up by hardware.
*/
-ENTRY(__clear_user)
+ENTRY(__arch_clear_user)
uaccess_enable_not_uao x2, x3, x4
mov x2, x1 // save the size for fixup return
subs x1, x1, #8
@@ -52,7 +52,7 @@ uao_user_alternative 9f, strb, sttrb, wz
5: mov x0, #0
uaccess_disable_not_uao x2, x3
ret
-ENDPROC(__clear_user)
+ENDPROC(__arch_clear_user)

.section .fixup,"ax"
.align 2
--- a/arch/arm64/lib/copy_in_user.S
+++ b/arch/arm64/lib/copy_in_user.S
@@ -64,14 +64,15 @@
.endm

end .req x5
-ENTRY(raw_copy_in_user)
+
+ENTRY(__arch_copy_in_user)
uaccess_enable_not_uao x3, x4, x5
add end, x0, x2
#include "copy_template.S"
uaccess_disable_not_uao x3, x4
mov x0, #0
ret
-ENDPROC(raw_copy_in_user)
+ENDPROC(__arch_copy_in_user)

.section .fixup,"ax"
.align 2