Coccinelle: Add api/memdup_user

/// Use kmemdup_user rather than duplicating its implementation

/// This is a little bit restricted to reduce false positives

///

// Confidence: High

// Copyright: (C) 2010 Nicolas Palix, DIKU.  GPLv2.

// Copyright: (C) 2010 Julia Lawall, DIKU.  GPLv2.

// Copyright: (C) 2010 Gilles Muller, INRIA/LiP6.  GPLv2.

// URL: http://coccinelle.lip6.fr/

// Comments:

// Options: -no_includes -include_headers

virtual patch

@@

expression from,to,size,flag;

position p;

identifier l1,l2;

@@

-  to = \(kmalloc@p\|kzalloc@p\)(size,flag);

+  to = memdup_user(from,size);

   if (

-      to==NULL

+      IS_ERR(to)

                 || ...) {

   <+... when != goto l1;

-  -ENOMEM

+  PTR_ERR(to)

   ...+>

   }

-  if (copy_from_user(to, from, size) != 0) {

-    <+... when != goto l2;

-    -EFAULT

-    ...+>

-  }