netdev - Re: [PATCH] mlx4: use snprintf() instead of sprintf() for safety

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Message-ID: <Y3zhL0/OItHF1R03@unreal>
Date:   Tue, 22 Nov 2022 16:48:15 +0200
From:   Leon Romanovsky <leon@...nel.org>
To:     Peter Kosyh <pkosyh@...dex.ru>
Cc:     Tariq Toukan <tariqt@...dia.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        lvc-project@...uxtesting.org
Subject: Re: [PATCH] mlx4: use snprintf() instead of sprintf() for safety

On Tue, Nov 22, 2022 at 04:04:53PM +0300, Peter Kosyh wrote:
> Use snprintf() to avoid the potential buffer overflow. Although in the
> current code this is hardly possible, the safety is unclean.

Let's fix the tools instead. The kernel code is correct.

Thanks

> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Signed-off-by: Peter Kosyh <pkosyh@...dex.ru>
> ---
>  drivers/net/ethernet/mellanox/mlx4/main.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c b/drivers/net/ethernet/mellanox/mlx4/main.c
> index d3fc86cd3c1d..0616d352451b 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/main.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/main.c
> @@ -3057,7 +3057,8 @@ static int mlx4_init_port_info(struct mlx4_dev *dev, int port)
>  		info->base_qpn = mlx4_get_base_qpn(dev, port);
>  	}
>  
> -	sprintf(info->dev_name, "mlx4_port%d", port);
> +	snprintf(info->dev_name, sizeof(info->dev_name),
> +		 "mlx4_port%d", port);
>  	info->port_attr.attr.name = info->dev_name;
>  	if (mlx4_is_mfunc(dev)) {
>  		info->port_attr.attr.mode = 0444;
> @@ -3077,7 +3078,8 @@ static int mlx4_init_port_info(struct mlx4_dev *dev, int port)
>  		return err;
>  	}
>  
> -	sprintf(info->dev_mtu_name, "mlx4_port%d_mtu", port);
> +	snprintf(info->dev_mtu_name, sizeof(info->dev_mtu_name),
> +		 "mlx4_port%d_mtu", port);
>  	info->port_mtu_attr.attr.name = info->dev_mtu_name;
>  	if (mlx4_is_mfunc(dev)) {
>  		info->port_mtu_attr.attr.mode = 0444;
> -- 
> 2.38.1
>