[PATCH 4.4 103/118] blackfin: fix copy_from_user()

[Greg Kroah-Hartman]

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

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

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 8f035983dd826d7e04f67b28acf8e2f08c347e41 upstream.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/blackfin/include/asm/uaccess.h |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/arch/blackfin/include/asm/uaccess.h
+++ b/arch/blackfin/include/asm/uaccess.h
@@ -177,11 +177,12 @@ static inline int bad_user_access_length
 static inline unsigned long __must_check
 copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-	if (access_ok(VERIFY_READ, from, n))
+	if (likely(access_ok(VERIFY_READ, from, n))) {
 		memcpy(to, (const void __force *)from, n);
-	else
-		return n;
-	return 0;
+		return 0;
+	}
+	memset(to, 0, n);
+	return n;
 }
 
 static inline unsigned long __must_check