linux-kernel - Re: [PATCH v2 03/24] drm/gud: use vmalloc

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Message-ID: <56f6fb34-f130-fddd-ca72-aa87362efd0c@tronnes.org>
Date:   Tue, 4 Jul 2023 12:41:08 +0200
From:   Noralf Trønnes <noralf@...nnes.org>
To:     Julia Lawall <Julia.Lawall@...ia.fr>
Cc:     kernel-janitors@...r.kernel.org, keescook@...omium.org,
        christophe.jaillet@...adoo.fr, kuba@...nel.org,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        noralf@...nnes.org
Subject: Re: [PATCH v2 03/24] drm/gud: use vmalloc_array and vcalloc



On 6/27/23 16:43, Julia Lawall wrote:
> Use vmalloc_array and vcalloc to protect against
> multiplication overflows.
> 
> The changes were done using the following Coccinelle
> semantic patch:
> 
> // <smpl>
> @initialize:ocaml@
> @@
> 
> let rename alloc =
>   match alloc with
>     "vmalloc" -> "vmalloc_array"
>   | "vzalloc" -> "vcalloc"
>   | _ -> failwith "unknown"
> 
> @@
>     size_t e1,e2;
>     constant C1, C2;
>     expression E1, E2, COUNT, x1, x2, x3;
>     typedef u8;
>     typedef __u8;
>     type t = {u8,__u8,char,unsigned char};
>     identifier alloc = {vmalloc,vzalloc};
>     fresh identifier realloc = script:ocaml(alloc) { rename alloc };
> @@
> 
> (
>       alloc(x1*x2*x3)
> |
>       alloc(C1 * C2)
> |
>       alloc((sizeof(t)) * (COUNT), ...)
> |
> -     alloc((e1) * (e2))
> +     realloc(e1, e2)
> |
> -     alloc((e1) * (COUNT))
> +     realloc(COUNT, e1)
> |
> -     alloc((E1) * (E2))
> +     realloc(E1, E2)
> )
> // </smpl>
> 
> Signed-off-by: Julia Lawall <Julia.Lawall@...ia.fr>
> 
> ---

Thanks, applied to drm-misc-next.

Noralf.

> v2: Use vmalloc_array and vcalloc instead of array_size.
> This also leaves a multiplication of a constant by a sizeof
> as is.  Two patches are thus dropped from the series.
> 
>  drivers/gpu/drm/gud/gud_pipe.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff -u -p a/drivers/gpu/drm/gud/gud_pipe.c b/drivers/gpu/drm/gud/gud_pipe.c
> --- a/drivers/gpu/drm/gud/gud_pipe.c
> +++ b/drivers/gpu/drm/gud/gud_pipe.c
> @@ -390,7 +390,7 @@ static int gud_fb_queue_damage(struct gu
>  	mutex_lock(&gdrm->damage_lock);
>  
>  	if (!gdrm->shadow_buf) {
> -		gdrm->shadow_buf = vzalloc(fb->pitches[0] * fb->height);
> +		gdrm->shadow_buf = vcalloc(fb->pitches[0], fb->height);
>  		if (!gdrm->shadow_buf) {
>  			mutex_unlock(&gdrm->damage_lock);
>  			return -ENOMEM;
>