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Date:   Sat, 20 Jun 2020 18:00:38 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     Luo bin <luobin9@huawei.com>
Cc:     davem@davemloft.net, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, luoxianjun@huawei.com,
        yin.yinshi@huawei.com, cloud.wangxiaoyun@huawei.com
Subject: Re: [PATCH net-next v1 5/5] hinic: add support to get eeprom
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Message-ID: <20200620160038.GQ304147@lunn.ch>
References: <20200620094258.13181-1-luobin9@huawei.com>
 <20200620094258.13181-6-luobin9@huawei.com>
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> +static int hinic_get_module_eeprom(struct net_device *netdev,
> +				   struct ethtool_eeprom *ee, u8 *data)
> +{
> +	struct hinic_dev *nic_dev = netdev_priv(netdev);
> +	u8 sfp_data[STD_SFP_INFO_MAX_SIZE];

sfp_data will contain whatever is on the stack.

> +	u16 len;
> +	int err;
> +
> +	if (!ee->len || ((ee->len + ee->offset) > STD_SFP_INFO_MAX_SIZE))
> +		return -EINVAL;
> +
> +	memset(data, 0, ee->len);

This clears what you are going to return.

> +
> +	err = hinic_get_sfp_eeprom(nic_dev->hwdev, sfp_data, &len);

Upto len bytes of sfp_data now contain useful data. The rest of
sfp_data is still stack data.


> +	if (err)
> +		return err;
> +
> +	memcpy(data, sfp_data + ee->offset, ee->len);

If len < ee->len, you have just returned to user space some stack data.

   Andrew