[PATCH 4.4 091/118] microblaze: fix copy_from_user()

From: Greg Kroah-Hartman
Date: Thu Sep 22 2016 - 15:00:21 EST


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

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

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit d0cf385160c12abd109746cad1f13e3b3e8b50b8 upstream.

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

---
arch/microblaze/include/asm/uaccess.h | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -373,10 +373,13 @@ extern long __user_bad(void);
static inline long copy_from_user(void *to,
const void __user *from, unsigned long n)
{
+ unsigned long res = n;
might_fault();
- if (access_ok(VERIFY_READ, from, n))
- return __copy_from_user(to, from, n);
- return n;
+ if (likely(access_ok(VERIFY_READ, from, n)))
+ res = __copy_from_user(to, from, n);
+ if (unlikely(res))
+ memset(to + (n - res), 0, res);
+ return res;
}

#define __copy_to_user(to, from, n) \