linux-kernel - Re: [PATCH v2] net: usb: rtl8150: prevent set_ethernet

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Message-ID: <81a5d8b6-5258-1f2e-15da-4324579799df@gmail.com>
Date:   Sun, 4 Oct 2020 02:28:14 +0530
From:   Anant Thazhemadam <anant.thazhemadam@...il.com>
To:     Joe Perches <joe@...ches.com>
Cc:     linux-kernel-mentees@...ts.linuxfoundation.org,
        syzbot+abbc768b560c84d92fd3@...kaller.appspotmail.com,
        Petko Manolov <petkan@...leusys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, linux-usb@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] net: usb: rtl8150: prevent set_ethernet_addr from
 setting uninit address


On 04/10/20 1:08 am, Joe Perches wrote:
> On Thu, 2020-10-01 at 13:02 +0530, Anant Thazhemadam wrote:
>> When get_registers() fails (which happens when usb_control_msg() fails)
>> in set_ethernet_addr(), the uninitialized value of node_id gets copied
>> as the address.
> unrelated trivia:
>
>> diff --git a/drivers/net/usb/rtl8150.c b/drivers/net/usb/rtl8150.c
> []
>> @@ -274,12 +274,17 @@ static int write_mii_word(rtl8150_t * dev, u8 phy, __u8 indx, u16 reg)
>>  		return 1;
>>  }
>>  
>> -static inline void set_ethernet_addr(rtl8150_t * dev)
>> +static bool set_ethernet_addr(rtl8150_t *dev)
>>  {
>>  	u8 node_id[6];
> This might be better as:
>
> 	u8 node_id[ETH_ALEN];
>
>> +	int ret;
>>  
>> -	get_registers(dev, IDR, sizeof(node_id), node_id);
>> -	memcpy(dev->netdev->dev_addr, node_id, sizeof(node_id));
>> +	ret = get_registers(dev, IDR, sizeof(node_id), node_id);
>> +	if (ret == sizeof(node_id)) {
>> +		memcpy(dev->netdev->dev_addr, node_id, sizeof(node_id));
> and
> 		ether_addr_copy(dev->netdev->dev_addr, node_id);
>
>
I will include this change as well, in the v3.
Thank you for pointing that out.

Thanks,
Anant