metag: copy_from_user() should zero the destination on access_ok() failure

[ Upstream commit 8ae95ed4ae5fc7c3391ed668b2014c9e2079533b ]

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

diff --git a/arch/metag/include/asm/uaccess.h b/arch/metag/include/asm/uaccess.h
index 0748b0a9798684c40eb02f5782472862245d9b78..7841f2290385fbe0b9ed7a8a1363ea3670197f02 100644 (file)
--- a/arch/metag/include/asm/uaccess.h
+++ b/arch/metag/include/asm/uaccess.h
@@ -199,8 +199,9 @@ extern unsigned long __must_check __copy_user_zeroing(void *to,
 static inline unsigned long
 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)))
                return __copy_user_zeroing(to, from, n);
+       memset(to, 0, n);
        return n;
 }