Coccinelle: Add null/kmerr.cocci

This semantic patch looks for kmalloc etc that are not followed by a
NULL check.  It only gives a report in the case where there is some
error handling code later in the function, which may be helpful
in determining what the error handling code for the call to kmalloc etc
should be.
Signed-off-by: Nicolas Palix <npalix@diku.dk>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/coccinelle/null/kmerr.cocci

+/// This semantic patch looks for kmalloc etc that are not followed by a
+/// NULL check.  It only gives a report in the case where there is some
+/// error handling code later in the function, which may be helpful
+/// in determining what the error handling code for the call to kmalloc etc
+/// should be.
+///
+// 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 context
+virtual org
+virtual report
+
+@withtest@
+expression x;
+position p;
+identifier f,fld;
+@@
+
+x@p = f(...);
+... when != x->fld
+\(x == NULL \| x != NULL\)
+
+@fixed depends on context && !org && !report@
+expression x,x1;
+position p1 != withtest.p;
+statement S;
+position any withtest.p;
+identifier f;
+@@
+
+*x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
+...
+*x1@p = f(...);
+if (!x1) S
+
+// ------------------------------------------------------------------------
+
+@rfixed depends on (org || report) && !context exists@
+expression x,x1;
+position p1 != withtest.p;
+position p2;
+statement S;
+position any withtest.p;
+identifier f;
+@@
+
+x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
+...
+x1@p = f@p2(...);
+if (!x1) S
+
+@script:python depends on org@
+p1 << rfixed.p1;
+p2 << rfixed.p2;
+@@
+
+cocci.print_main("alloc call",p1)
+cocci.print_secs("possible model",p2)
+
+@script:python depends on report@
+p1 << rfixed.p1;
+p2 << rfixed.p2;
+@@
+
+msg = "alloc with no test, possible model on line %s" % (p2[0].line)
+coccilib.report.print_report(p1[0],msg)