scripts/coccinelle: add some more coccinelle tests

Add some useful static code analysis scripts for coccinelle
copied from the Linux kernel v4.14-rc8:

Warn on check against NULL before calling free.
scripts/coccinelle/free/ifnullfree.cocci

Detect superfluous NULL check for list iterator.
scripts/coccinelle/iterators/itnull.cocci

Check if list iterator is reassigned.
scripts/coccinelle/iterators/list_entry_update.cocci

Check if list iterator is used after loop.
scripts/coccinelle/iterators/use_after_iter.cocci

Find wrong argument of sizeof in allocation function:
scripts/coccinelle/misc/badty.cocci

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

1 files changed, 94 insertions, 0 deletions

diff --git a/scripts/coccinelle/iterators/itnull.cocci b/scripts/coccinelle/iterators/itnull.cocci
new file mode 100644
index 0000000000..f58732b56a
--- /dev/null
+++ b/scripts/coccinelle/iterators/itnull.cocci
@@ -0,0 +1,94 @@
+/// Many iterators have the property that the first argument is always bound
+/// to a real list element, never NULL.
+//# False positives arise for some iterators that do not have this property,
+//# or in cases when the loop cursor is reassigned.  The latter should only
+//# happen when the matched code is on the way to a loop exit (break, goto,
+//# or return).
+///
+// Confidence: Moderate
+// Copyright: (C) 2010-2012 Nicolas Palix.  GPLv2.
+// Copyright: (C) 2010-2012 Julia Lawall, INRIA/LIP6.  GPLv2.
+// Copyright: (C) 2010-2012 Gilles Muller, INRIA/LiP6.  GPLv2.
+// URL: http://coccinelle.lip6.fr/
+// Comments:
+// Options: --no-includes --include-headers
+
+virtual patch
+virtual context
+virtual org
+virtual report
+
+@depends on patch@
+iterator I;
+expression x,E,E1,E2;
+statement S,S1,S2;
+@@
+
+I(x,...) { <...
+(
+- if (x == NULL && ...) S
+|
+- if (x != NULL || ...)
+  S
+|
+- (x == NULL) ||
+  E
+|
+- (x != NULL) &&
+  E
+|
+- (x == NULL && ...) ? E1 :
+  E2
+|
+- (x != NULL || ...) ?
+  E1
+- : E2
+|
+- if (x == NULL && ...) S1 else
+  S2
+|
+- if (x != NULL || ...)
+  S1
+- else S2
+|
++ BAD(
+  x == NULL
++ )
+|
++ BAD(
+  x != NULL
++ )
+)
+  ...> }
+
+@r depends on !patch exists@
+iterator I;
+expression x,E;
+position p1,p2;
+@@
+
+*I@p1(x,...)
+{ ... when != x = E
+(
+*  x@p2 == NULL
+|
+*  x@p2 != NULL
+)
+  ... when any
+}
+
+@script:python depends on org@
+p1 << r.p1;
+p2 << r.p2;
+@@
+
+cocci.print_main("iterator-bound variable",p1)
+cocci.print_secs("useless NULL test",p2)
+
+@script:python depends on report@
+p1 << r.p1;
+p2 << r.p2;
+@@
+
+msg = "ERROR: iterator variable bound on line %s cannot be NULL" % (p1[0].line)
+coccilib.report.print_report(p2[0], msg)