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Message-ID: <30715dc4-3285-4f4a-a041-a718a8509721@embeddedor.com>
Date: Sat, 10 Feb 2024 10:49:57 -0600
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Subject: Re: [PATCH] drm/xe: Prefer struct_size over open coded arithmetic
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To: Erick Archer <erick.archer@gmx.com>,
 Lucas De Marchi <lucas.demarchi@intel.com>, Oded Gabbay
 <ogabbay@kernel.org>, =?UTF-8?Q?Thomas_Hellstr=C3=B6m?=
 <thomas.hellstrom@linux.intel.com>,
 Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
 Maxime Ripard <mripard@kernel.org>, Thomas Zimmermann <tzimmermann@suse.de>,
 David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
 "Gustavo A. R. Silva" <gustavoars@kernel.org>,
 Kees Cook <keescook@chromium.org>
Cc: intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
 linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
References: <20240210141913.6611-1-erick.archer@gmx.com>
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
In-Reply-To: <20240210141913.6611-1-erick.archer@gmx.com>
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On 2/10/24 08:19, Erick Archer wrote:
> This is an effort to get rid of all multiplications from allocation
> functions in order to prevent integer overflows [1].
> 
> As the "q" variable is a pointer to "struct xe_exec_queue" and this
> structure ends in a flexible array:
> 
> struct xe_exec_queue {
> 	[...]
> 	struct xe_lrc lrc[];
> };
> 
> the preferred way in the kernel is to use the struct_size() helper to
> do the arithmetic instead of the argument "size + size * count" in the
> kzalloc() function.
> 
> This way, the code is more readable and more safer.
> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Link: https://github.com/KSPP/linux/issues/160 [2]
> Signed-off-by: Erick Archer <erick.archer@gmx.com>

LGTM:

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks!
-- 
Gustavo

> ---
>   drivers/gpu/drm/xe/xe_exec_queue.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c
> index bcfc4127c7c5..f4e53cbccd04 100644
> --- a/drivers/gpu/drm/xe/xe_exec_queue.c
> +++ b/drivers/gpu/drm/xe/xe_exec_queue.c
> @@ -44,7 +44,7 @@ static struct xe_exec_queue *__xe_exec_queue_create(struct xe_device *xe,
>   	/* only kernel queues can be permanent */
>   	XE_WARN_ON((flags & EXEC_QUEUE_FLAG_PERMANENT) && !(flags & EXEC_QUEUE_FLAG_KERNEL));
> 
> -	q = kzalloc(sizeof(*q) + sizeof(struct xe_lrc) * width, GFP_KERNEL);
> +	q = kzalloc(struct_size(q, lrc, width), GFP_KERNEL);
>   	if (!q)
>   		return ERR_PTR(-ENOMEM);
> 
> --
> 2.25.1
> 
>