linux-kernel - Re: [PATCH V3] scripts/coccinelle/free: add NULL test before freeing functions

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Date:	Sat, 28 Jun 2014 19:58:13 +0200 (CEST)
From:	Julia Lawall <julia.lawall@...6.fr>
To:	Fabian Frederick <fabf@...net.be>
cc:	linux-kernel@...r.kernel.org,
	Gilles Muller <Gilles.Muller@...6.fr>,
	Joe Perches <joe@...ches.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Marek <mmarek@...e.cz>
Subject: Re: [PATCH V3] scripts/coccinelle/free: add NULL test before freeing
 functions



On Sat, 28 Jun 2014, Julia Lawall wrote:

> On Sat, 28 Jun 2014, Fabian Frederick wrote:
>
> > Warns or generates patch for NULL check before the following functions:
> >
> > kfree
> > usb_free_urb
> > debugfs_remove
> > debugfs_remove_recursive
> >
> > Cc: Julia Lawall <Julia.Lawall@...6.fr>
> > Cc: Gilles Muller <Gilles.Muller@...6.fr>
> > Cc: Joe Perches <joe@...ches.com>
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Signed-off-by: Fabian Frederick <fabf@...net.be>
>
> Acked-by: Julia Lawall <Julia.Lawall@...6.fr>
>
> > ---
> >
> > V3:
> >    -Update print_main message.
> >    -Add patch mode (suggested by Julia Lawall)
> >
> > V2:
> >    -Add 3 more functions to kfree (suggested by Joe Perches)
> >    -Update warning message to involve code analysis (suggested by Julia Lawall)
> >
> >  scripts/coccinelle/free/ifnullfree.cocci | 53 ++++++++++++++++++++++++++++++++
> >  1 file changed, 53 insertions(+)
> >  create mode 100644 scripts/coccinelle/free/ifnullfree.cocci
> >
> > diff --git a/scripts/coccinelle/free/ifnullfree.cocci b/scripts/coccinelle/free/ifnullfree.cocci
> > new file mode 100644
> > index 0000000..c826d98
> > --- /dev/null
> > +++ b/scripts/coccinelle/free/ifnullfree.cocci
> > @@ -0,0 +1,53 @@
> > +/// NULL check before some freeing functions is not needed.
> > +///
> > +/// Based on checkpatch warning
> > +/// "kfree(NULL) is safe this check is probably not required"
> > +/// and kfreeaddr.cocci by Julia Lawall.
> > +///
> > +/// Comments: -
> > +/// Options: --no-includes --include-headers
> > +
> > +virtual patch
> > +virtual org
> > +virtual report
> > +virtual context
> > +
> > +@r2 depends on patch@
> > +expression E;
> > +@@
> > +- if (E)
> > +(
> > +-	kfree(E);
> > ++ kfree(E);
> > +|
> > +-	debugfs_remove(E);
> > ++ debugfs_remove(E);
> > +|
> > +-	debugfs_remove_recursive(E);
> > ++ debugfs_remove_recursive(E);
> > +|
> > +-	usb_free_urb(E);
> > ++ usb_free_urb(E);
> > +)
> > +
> > +@r depends on context || report || org @
> > +expression E;
> > +position p;
> > +@@
> > +
> > +* if (E)
> > +*	\(kfree@p\|debugfs_remove@p\|debugfs_remove_recursive@p\|usb_free_urb\)(E);
> > +
> > +@...ipt:python depends on org@
> > +p << r.p;
> > +@@
> > +
> > +cocci.print_main("NULL check before that freeing function is not needed", p)
> > +
> > +@...ipt:python depends on report@
> > +p << r.p;
> > +@@
> > +
> > +msg = "WARNING: NULL check before freeing functions like kfree, debugfs_remove, debugfs_remove_recursive or usb_free_urb is not needed. Maybe consider reorganizing relevant code to avoid passing NULL values."
> > +coccilib.report.print_report(p[0], msg)
> > +
> > --
> > 1.8.4.5
> >
> >
>
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