linux-kernel - Re: [Cocci] [PATCH] coccinelle: misc: add array_size_dup script to detect missed overlow checks

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Date:   Wed, 17 Jun 2020 22:15:07 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...ia.fr>
To:     Denis Efremov <efremov@...ux.com>
cc:     linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        cocci@...teme.lip6.fr
Subject: Re: [Cocci] [PATCH] coccinelle: misc: add array_size_dup script to
 detect missed overlow checks

On Wed, 17 Jun 2020, Julia Lawall wrote:

>
>
> On Wed, 17 Jun 2020, Denis Efremov wrote:
>
> >
> > >
> > > Awesome! I'll take a look into this. :)
> > >
> > Here is another script for your #83 ticket.
> > Currently, it issues 598 warnings.
> >
> > // SPDX-License-Identifier: GPL-2.0-only
> > ///
> > /// Check for missing overflow checks in allocation functions.
> > /// Low confidence because it's pointless to check for overflow
> > /// relatively small allocations.
> > ///
> > // Confidence: Low
> > // Copyright: (C) 2020 Denis Efremov ISPRAS
> > // Options: --no-includes --include-headers
> >
> > virtual patch
> > virtual context
> > virtual org
> > virtual report
> >
> > @depends on patch@
> > expression E1, E2, E3, E4, size;
> > @@
> >
> > (
> > - 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);
>
> Should the arguments be checked to see if they have something to do with
> arrays and structures?

Sorry for the noise, I see that this comment makes no sense.

julia

>
> > )
> >   ... when != size = E4
> >       when != size += E4
> >       when != size -= E4
> >       when != size *= E4
>
> Here you can have a metavariable
>
> assignment operator aop;
>
> and then say size aop E4
>
> It doesn't really look like an assignment any more, but it could be a
> little safer.
>
> julia
>
> >       when != &size
> >   \(kmalloc\|krealloc\|kzalloc\|kzalloc_node\|
> >     vmalloc\|vzalloc\|vzalloc_node\|
> >     kvmalloc\|kvzalloc\|kvzalloc_node\|
> >     sock_kmalloc\|
> >     f2fs_kmalloc\|f2fs_kzalloc\|f2fs_kvmalloc\|f2fs_kvzalloc\|
> >     devm_kmalloc\|devm_kzalloc\)
> >   (..., size, ...)
> >
> > @r depends on !patch@
> > expression E1, E2, E3, E4, size;
> > position p;
> > @@
> >
> > (
> > * size = E1 * E2;@p
> > |
> > * size = E1 * E2 * E3;@p
> > |
> > * size = E1 * E2 + E3;@p
> > )
> >   ... when != size = E4
> >       when != size += E4
> >       when != size -= E4
> >       when != size *= E4
> >       when != &size
> > * \(kmalloc\|krealloc\|kzalloc\|kzalloc_node\|
> >     vmalloc\|vzalloc\|vzalloc_node\|
> >     kvmalloc\|kvzalloc\|kvzalloc_node\|
> >     sock_kmalloc\|
> >     f2fs_kmalloc\|f2fs_kzalloc\|f2fs_kvmalloc\|f2fs_kvzalloc\|
> >     devm_kmalloc\|devm_kzalloc\)
> >   (..., size, ...)
> >
> > @script:python depends on report@
> > p << r.p;
> > @@
> >
> > coccilib.report.print_report(p[0], "WARNING: missing overflow check")
> >
> > @script:python depends on org@
> > p << r.p;
> > @@
> >
> > coccilib.org.print_todo(p[0], "WARNING: missing overflow check")
> > _______________________________________________
> > Cocci mailing list
> > Cocci@...teme.lip6.fr
> > https://systeme.lip6.fr/mailman/listinfo/cocci
> >
> _______________________________________________
> Cocci mailing list
> Cocci@...teme.lip6.fr
> https://systeme.lip6.fr/mailman/listinfo/cocci
>

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