include/linux/uaccess.h | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 39c7cf82b0c2..43844510d5d0 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -38,6 +38,7 @@
 #else
  #define can_do_masked_user_access() 0
  #define masked_user_access_begin(src) NULL
+ #define mask_user_address(src) (src)
 #endif
 
 /*
@@ -159,19 +160,27 @@ _inline_copy_from_user(void *to, const void __user *from, unsigned long n)
 {
 	unsigned long res = n;
 	might_fault();
-	if (!should_fail_usercopy() && likely(access_ok(from, n))) {
+	if (should_fail_usercopy())
+		goto fail;
+	if (can_do_masked_user_access())
+		from = mask_user_address(from);
+	else {
+		if (!access_ok(from, n))
+			goto fail;
 		/*
 		 * Ensure that bad access_ok() speculation will not
 		 * lead to nasty side effects *after* the copy is
 		 * finished:
 		 */
 		barrier_nospec();
-		instrument_copy_from_user_before(to, from, n);
-		res = raw_copy_from_user(to, from, n);
-		instrument_copy_from_user_after(to, from, n, res);
 	}
-	if (unlikely(res))
-		memset(to + (n - res), 0, res);
+	instrument_copy_from_user_before(to, from, n);
+	res = raw_copy_from_user(to, from, n);
+	instrument_copy_from_user_after(to, from, n, res);
+	if (likely(!res))
+		return 0;
+fail:
+	memset(to + (n - res), 0, res);
 	return res;
 }
 extern __must_check unsigned long