Message-ID: <cc8714ba-f840-6856-3385-1bffaf6631e7@huawei.com>
Date:   Fri, 19 Nov 2021 11:37:07 +0800
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Subject: Re: [PATCH] ethernet: hisilicon: hns: hns_dsaf_misc: fix a possible
 array overflow in hns_dsaf_ge_srst_by_port()
To:     Teng Qi <starmiku1207184332@gmail.com>, <yisen.zhuang@huawei.com>,
        <salil.mehta@huawei.com>, <davem@davemloft.net>, <kuba@kernel.org>,
        <huangguangbin2@huawei.com>, <zhengyongjun3@huawei.com>,
        <liuyonglong@huawei.com>, <shenyang39@huawei.com>
CC:     <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <baijiaju1990@gmail.com>, <islituo@gmail.com>,
        TOTE Robot <oslab@tsinghua.edu.cn>
References: <20211117034453.28963-1-starmiku1207184332@gmail.com>
From:   "lipeng (Y)" <lipeng321@huawei.com>
In-Reply-To: <20211117034453.28963-1-starmiku1207184332@gmail.com>
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Sorry for the late reply.

Seeing this functions:

static int hns_mac_get_max_port_num(struct dsaf_device *dsaf_dev)
{
     if (HNS_DSAF_IS_DEBUG(dsaf_dev))
         return 1;
     else
         return  DSAF_MAX_PORT_NUM;
}

int hns_mac_init(struct dsaf_device *dsaf_dev)
{
     bool found = false;
     int ret;
     u32 port_id;
     int max_port_num = hns_mac_get_max_port_num(dsaf_dev);
     struct hns_mac_cb *mac_cb;
     struct fwnode_handle *child;

     device_for_each_child_node(dsaf_dev->dev, child) {
         ret = fwnode_property_read_u32(child, "reg", &port_id);
         if (ret) {
             dev_err(dsaf_dev->dev,
                 "get reg fail, ret=%d!\n", ret);
             return ret;
         }
         if (port_id >= max_port_num) {
             dev_err(dsaf_dev->dev,
                 "reg(%u) out of range!\n", port_id);
             return -EINVAL;
         }

The port_id had limit to DSAF_MAX_PORT_NUM, so this patch is 
unnecessary, thanks!


On 2021/11/17 11:44, Teng Qi wrote:
> The if statement:
>    if (port >= DSAF_GE_NUM)
>          return;
> 
> limits the value of port less than DSAF_GE_NUM (i.e., 8).
> However, if the value of port is 6 or 7, an array overflow could occur:
>    port_rst_off = dsaf_dev->mac_cb[port]->port_rst_off;
> 
> because the length of dsaf_dev->mac_cb is DSAF_MAX_PORT_NUM (i.e., 6).
> 
> To fix this possible array overflow, we first check port and if it is
> greater than or equal to DSAF_MAX_PORT_NUM, the function returns.
> 
> Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
> Signed-off-by: Teng Qi <starmiku1207184332@gmail.com>
> ---
>   drivers/net/ethernet/hisilicon/hns/hns_dsaf_misc.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/ethernet/hisilicon/hns/hns_dsaf_misc.c b/drivers/net/ethernet/hisilicon/hns/hns_dsaf_misc.c
> index 23d9cbf262c3..740850b64aff 100644
> --- a/drivers/net/ethernet/hisilicon/hns/hns_dsaf_misc.c
> +++ b/drivers/net/ethernet/hisilicon/hns/hns_dsaf_misc.c
> @@ -400,6 +400,10 @@ static void hns_dsaf_ge_srst_by_port(struct dsaf_device *dsaf_dev, u32 port,
>   		return;
>   
>   	if (!HNS_DSAF_IS_DEBUG(dsaf_dev)) {
> +		/* DSAF_MAX_PORT_NUM is 6, but DSAF_GE_NUM is 8.
> +		   We need check to prevent array overflow */
> +		if (port >= DSAF_MAX_PORT_NUM)
> +			return;
>   		reg_val_1  = 0x1 << port;
>   		port_rst_off = dsaf_dev->mac_cb[port]->port_rst_off;
>   		/* there is difference between V1 and V2 in register.*/
>