[PATCH 3.16 289/346] sh: fix copy_from_user()

[Ben Hutchings]

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 6e050503a150b2126620c1a1e9b3a368fcd51eac upstream.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 arch/sh/include/asm/uaccess.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/arch/sh/include/asm/uaccess.h
+++ b/arch/sh/include/asm/uaccess.h
@@ -151,7 +151,10 @@ copy_from_user(void *to, const void __us
 	__kernel_size_t __copy_size = (__kernel_size_t) n;
 
 	if (__copy_size && __access_ok(__copy_from, __copy_size))
-		return __copy_user(to, from, __copy_size);
+		__copy_size = __copy_user(to, from, __copy_size);
+
+	if (unlikely(__copy_size))
+		memset(to + (n - __copy_size), 0, __copy_size);
 
 	return __copy_size;
 }