[PATCH 4.15 056/202] [Variant 1/Spectre-v1] arm64: uaccess: Mask __user pointers for __arch_{clear, copy_*}_user

[Greg Kroah-Hartman]

4.15-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: 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