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From: Kees Cook <keescook@chromium.org>
To: Julia Lawall <julia.lawall@inria.fr>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>,
	cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org
Subject: Re: [Cocci] [PATCH] coccinelle: misc: add array_size_dup script to detect missed overlow checks
Date: Thu, 18 Jun 2020 12:52:50 -0700
Message-ID: <202006181249.8B826D9@keescook> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2006172051280.3083@hadrien>

On Wed, Jun 17, 2020 at 08:54:03PM +0200, Julia Lawall wrote:
> 
> 
> On Wed, 17 Jun 2020, Kees Cook wrote:
> 
> > On Mon, Jun 15, 2020 at 01:20:45PM +0300, Denis Efremov wrote:
> > > +@as@
> > > +expression E1, E2;
> > > +@@
> > > +
> > > +array_size(E1, E2)
> >
> > BTW, is there a way yet in Coccinelle to match a fully qualified (?)
> > identifier? For example, if I have two lines in C:
> >
> > A)
> > 	array_size(variable, 5);
> > B)
> > 	array_size(instance->member.size, 5);
> > C)
> > 	array_size(instance->member.size + 1, 5);
> > D)
> > 	array_size(function_call(variable), 5);
> >
> >
> > This matches A, B, C, and D:
> >
> > @@
> > expression ARG1;
> > expression ARG2;
> > @@
> >
> > array_size(ARG1, ARG2);
> >
> >
> > This matches only A:
> >
> > @@
> > identifier ARG1;
> > expression ARG2;
> > @@
> >
> > array_size(ARG1, ARG2);
> >
> >
> > How do I get something to match A and B but not C and D (i.e. I do not
> > want to match any operations, function calls, etc, only a variable,
> > which may be identified through dereference, array index, or struct
> > member access.)
> 
> \(i\|e.fld\|e->fld\)
> 
> would probably do what you want.  It will also match cases where e is a
> function/macr call, but that is unlikely.
> 
> If you want a single metavariable that contains the whole thing, you can
> have an expression metavariable E and then write:
> 
> \(\(i\|e.fld\|e->fld\) \& E\)

Can you give an example of how that would look for an @@ section?

The problem I have is that I don't know the depth or combination of such
metavariables. There are a lot of combinations:

a
	a.b
		a.b.c
			a.b.c.d
			a.b.c->d
		a.b->c
			a.b->c.d
			a.b->c->d
	a->b
		a->b.c
			a->b.c.d
			a->b.c->d
		a->b->c
			a->b->c.d
			a->b->c->d
...


-- 
Kees Cook
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Cocci@systeme.lip6.fr
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Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-15 10:20 Denis Efremov
2020-06-15 18:23 ` Kees Cook
2020-06-15 18:35   ` Denis Efremov
2020-06-15 18:46     ` Gustavo A. R. Silva
2020-06-17  9:32       ` Denis Efremov
2020-06-17 10:55       ` Denis Efremov
2020-06-17 20:08         ` Julia Lawall
2020-06-17 20:15           ` Julia Lawall
2020-06-17 18:15 ` Kees Cook
2020-06-17 18:54   ` Julia Lawall
2020-06-18 19:52     ` Kees Cook [this message]
2020-06-18 19:56       ` Julia Lawall
2020-06-18 20:48         ` Kees Cook
2020-06-18 21:08           ` Julia Lawall
2020-06-17 20:30 ` Julia Lawall
2020-06-17 20:50   ` Denis Efremov
2020-06-17 20:52     ` Julia Lawall
2020-06-18 10:23 ` [Cocci] [PATCH v2] " Denis Efremov
2020-06-19 13:13 ` [Cocci] [PATCH v3] coccinelle: misc: add array_size_dup script to detect missed overflow checks Denis Efremov
2020-06-21 20:53   ` Julia Lawall
2020-06-21 20:56   ` Julia Lawall
2020-06-22 12:12     ` Denis Efremov
2020-06-22 12:16     ` Denis Efremov
2020-06-22 12:19       ` Julia Lawall
2020-06-22 22:10 ` [Cocci] [PATCH v4] " Denis Efremov
2020-06-24 19:42   ` Julia Lawall

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