From: Julia Lawall <julia.lawall@inria.fr>
To: Kees Cook <kees@kernel.org>
Cc: cocci@inria.fr
Subject: Re: [cocci] __free() attribute inhibits matching?
Date: Thu, 20 Mar 2025 00:25:00 +0100 (CET) [thread overview]
Message-ID: <1b774129-badf-f889-8d3c-c6492097d3f@inria.fr> (raw)
In-Reply-To: <202503191424.2FA8A7E@keescook>
On Wed, 19 Mar 2025, Kees Cook wrote:
> On Wed, Mar 19, 2025 at 08:44:38AM +0100, Julia Lawall wrote:
> > On Tue, 18 Mar 2025, Kees Cook wrote:
> > > On Tue, Mar 18, 2025 at 06:56:40PM +0100, Julia Lawall wrote:
> > > > I think you want
> > > >
> > > > Expression *m;
> > > >
> > > > A->@m b
> > > >
> > > > B would be an identifier
> > >
> > > But how does "B" get correctly type restricted? (Or in my example,
> > > "NAME"?)
> > >
> > > I tried:
> > >
> > > @direct depends on !(file in "tools") && !(file in "samples")@
> > > type TYPE;
> > > TYPE *P;
> > > TYPE *MEMBER;
> > > TYPE INST;
> > > identifier NAME;
> > > expression COMP;
> > > identifier ALLOC =~ "^kv?[mz]alloc";
> > > fresh identifier ALLOC_OBJ = ALLOC ## "_obj";
> > > @@
> > >
> > > \(\(P\|COMP.@MEMBER NAME\|COMP->@MEMBER NAME\) \& VAR\)
> > > - = ALLOC((\(sizeof(*VAR)\|sizeof(TYPE)\|sizeof(INST)\)), GFP);
> > > + = ALLOC_OBJ(*VAR, GFP);
> > >
> > > This parses, but don't match (from crypto/asymmetric_keys/x509_cert_parser.c):
> > >
> > > cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
> > >
> > > But does match (via "P"):
> > >
> > > cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
> >
> > What is the command line, eg --all-includes? You can try
> > --verbose-includes to see what is happening with #include "x509_parser.h"
>
> Okay, my hiccups continue.
>
> I do not seem to be able to mix a "type" metavariable with anything else.
> For example, instead of these rules repeated:
>
> @direct depends on patch@
> type TYPE;
> TYPE INST;
> identifier PTR;
> expression GFP;
> expression TYPED;
> identifier ALLOC =~ "^kv?[mz]alloc$";
> fresh identifier ALLOC_OBJ = ALLOC ## "_obj";
> @@
>
> (
> TYPE *PTR
> - = ALLOC((sizeof(*PTR)), GFP);
> + = ALLOC_OBJ(*PTR, GFP);
> |
> TYPE *PTR
> - = ALLOC((sizeof(INST)), GFP);
> + = ALLOC_OBJ(INST, GFP);
> |
> TYPE *PTR
> - = ALLOC((sizeof(TYPE)), GFP);
> + = ALLOC_OBJ(TYPE, GFP);
> )
>
> I wanted to write it as:
>
> TYPE *PTR
> - = ALLOC((sizeof(\(\(*PTR\|INST\|TYPE\) \& TYPED\))), GFP);
> + = ALLOC_OBJ(TYPED, GFP);
>
> But this doesn't let me even put "TYPE" in the \( \) at all, much less
> put it into the TYPED expression:
>
> minus: parse error:
> File "scripts/coccinelle/api/kmalloc_objs.cocci", line 55, column 34, charpos = 1235
> around = 'TYPE',
> whole content = - = ALLOC((sizeof(\(\(*PTR\|INST\|TYPE\) \& TYPED\))), GFP);
>
> How do I collapse these three into 1 rule?
A disjunction has to have the same kind of thing in every branch. INST is
an expression but TYPE is a type, so that doesn't work. sizeof is
misleading. There are actually two different sizeof's, one where the
argument is an expression and one where the argument is a type. One
requires () around the argument while the other does not.
You can just make a () with three copies of sizeof, or even two copies of
sizeof, on for TYPE and one for a disjunction of the other possibilities.
julia
next prev parent reply other threads:[~2025-03-19 23:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-17 18:44 [cocci] __free() attribute inhibits matching? Kees Cook
2025-03-17 20:59 ` Julia Lawall
2025-03-17 23:02 ` Kees Cook
2025-03-17 23:13 ` Julia Lawall
2025-03-18 15:39 ` Kees Cook
2025-03-18 15:43 ` Julia Lawall
2025-03-18 16:30 ` Kees Cook
2025-03-18 17:56 ` Julia Lawall
2025-03-19 3:31 ` Kees Cook
2025-03-19 5:55 ` Julia Lawall
2025-03-19 7:20 ` [cocci] Checking the determination of type information? Markus Elfring
2025-03-19 7:44 ` [cocci] __free() attribute inhibits matching? Julia Lawall
2025-03-19 20:06 ` Kees Cook
2025-03-19 21:30 ` Kees Cook
2025-03-19 23:25 ` Julia Lawall [this message]
2025-03-21 13:52 ` Markus Elfring
2025-03-19 10:24 ` Markus Elfring
2025-03-19 10:57 ` Markus Elfring
2025-03-18 17:43 ` Markus Elfring
2025-03-18 18:02 ` Kees Cook
2025-03-18 19:18 ` Markus Elfring
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