linux-kernel - Re: [PATCH] coccinelle: misc: Add array_size_dup script to detect missed overflow checks

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Date:   Wed, 17 Jun 2020 16:36:07 +0200
From:   Markus Elfring <Markus.Elfring@....de>
To:     Denis Efremov <efremov@...ux.com>,
        "Gustavo A. R. Silva" <garsilva@...eddedor.com>,
        Kees Cook <keescook@...omium.org>,
        Coccinelle <cocci@...teme.lip6.fr>
Cc:     linux-kernel@...r.kernel.org, Julia Lawall <julia.lawall@...6.fr>
Subject: Re: [PATCH] coccinelle: misc: Add array_size_dup script to detect
 missed overflow checks

I propose once more to avoid a typo in the previous patch subject.


…
> (
> - size = E1 * E2;
> + size = array_size(E1, E2);
> |
> - size = E1 * E2 * E3;
> + size = array3_size(E1, E2, E3);
> |
> - size = E1 * E2 + E3;
> + size = struct_size(E1, E2, E3);
> )

How do you think about to use SmPL disjunctions like the following?

 size =
(
-       (E1) * (E2)
+       array_size(E1, E2)
|
-       (E1) * (E2) * (E3)
+       array3_size(E1, E2, E3)
|
-       (E1) * (E2) + (E3)
+       struct_size(E1, E2, E3)
);


>   ... when != size = E4
>       when != size += E4
…

Can it become helpful to express a constraint for a metavariable of
the type “assignment operator”?


> (
> * size = E1 * E2;@p
> |
> * size = E1 * E2 * E3;@p
> |
> * size = E1 * E2 + E3;@p
> )

*size =@p \( (E1) * (E2) \| (E1) * (E2) * (E3) \| (E1) * (E2) + (E3) \)

Regards,
Markus