scripts/coccinelle: check for field address argument to kfree

The argument to kfree should not be the address of a structure field.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/coccinelle/free/kfreeaddr.cocci

+/// Free of a structure field
+///
+// Confidence: High
+// Copyright: (C) 2013 Julia Lawall, INRIA/LIP6.  GPLv2.
+// URL: http://coccinelle.lip6.fr/
+// Comments:
+// Options: -no_includes -include_headers
+
+virtual org
+virtual report
+virtual context
+
+@r depends on context || report || org @
+expression e;
+identifier f;
+position p;
+@@
+
+* kfree@p(&e->f)
+
+@script:python depends on org@
+p << r.p;
+@@
+
+cocci.print_main("kfree",p)
+
+@script:python depends on report@
+p << r.p;
+@@
+
+msg = "ERROR: kfree of structure field"
+coccilib.report.print_report(p[0],msg)