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References: <20230623211457.102544-1-Julia.Lawall@inria.fr> <20230623211457.102544-18-Julia.Lawall@inria.fr>
In-Reply-To: <20230623211457.102544-18-Julia.Lawall@inria.fr>
From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Sat, 24 Jun 2023 07:34:52 +0200
Message-ID: <CACT4Y+ayUeSpdmkec3pCna1kVSd1QTgBYLAb3zNJJ-7wcDHGdQ@mail.gmail.com>
Subject: Re: [PATCH 17/26] kcov: use array_size
To:     Julia.Lawall@inria.fr
Cc:     keescook@chromium.org, kernel-janitors@vger.kernel.org,
        Andrey Konovalov <andreyknvl@gmail.com>,
        kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org
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On Fri, 23 Jun 2023 at 23:15, Julia Lawall <Julia.Lawall@inria.fr> wrote:
>
> Use array_size to protect against multiplication overflows.
>
> The changes were done using the following Coccinelle semantic patch:
>
> // <smpl>
> @@
>     expression E1, E2;
>     constant C1, C2;
>     identifier alloc = {vmalloc,vzalloc};
> @@
>
> (
>       alloc(C1 * C2,...)
> |
>       alloc(
> -           (E1) * (E2)
> +           array_size(E1, E2)
>       ,...)
> )
> // </smpl>
>
> Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>

Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

> ---
>  kernel/kcov.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/kcov.c b/kernel/kcov.c
> index 84c717337df0..631444760644 100644
> --- a/kernel/kcov.c
> +++ b/kernel/kcov.c
> @@ -900,7 +900,7 @@ void kcov_remote_start(u64 handle)
>         /* Can only happen when in_task(). */
>         if (!area) {
>                 local_unlock_irqrestore(&kcov_percpu_data.lock, flags);
> -               area = vmalloc(size * sizeof(unsigned long));
> +               area = vmalloc(array_size(size, sizeof(unsigned long)));
>                 if (!area) {
>                         kcov_put(kcov);
>                         return;
>