nios2: copy_from_user() should zero the tail of destination

[ Upstream commit e33d1f6f72cc82fcfc3d1fb20c9e3ad83b1928fa ]

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

diff --git a/arch/nios2/include/asm/uaccess.h b/arch/nios2/include/asm/uaccess.h
index caa51ff85a3c7d0ac7c57cf034758185aad64724..2b4b9e91967525b722990ba4796324be523a1f9d 100644 (file)
--- 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,