nios2: copy_from_user() should zero the tail of destination

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 6 insertions, 3 deletions

diff --git a/arch/nios2/include/asm/uaccess.h b/arch/nios2/include/asm/uaccess.h
index caa51ff85a3c..2b4b9e919675 100644
--- a/arch/nios2/include/asm/uaccess.h
+++ b/arch/nios2/include/asm/uaccess.h
@@ -102,9 +102,12 @@ extern long __copy_to_user(void __user *to, const void *from, unsigned long n);
 static inline long copy_from_user(void *to, const void __user *from,
                                 unsigned long n)
 {
-        if (!access_ok(VERIFY_READ, from, n))
-                return n;
-        return __copy_from_user(to, from, n);
+        unsigned long res = n;
+        if (access_ok(VERIFY_READ, from, n))
+                res = __copy_from_user(to, from, n);
+        if (unlikely(res))
+                memset(to + (n - res), 0, res);
+        return res;
 }
 
 static inline long copy_to_user(void __user *to, const void *from,