linux-kernel - Re: [PATCH net-next] net: ethtool: Fix out-of-bounds copy to user

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Message-ID: <034f5393-e519-1e8d-af76-ae29677a1bf5@sangfor.com.cn>
Date:   Thu, 8 Jun 2023 17:06:31 +0800
From:   Ding Hui <dinghui@...gfor.com.cn>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Alexander Duyck <alexander.duyck@...il.com>,
        Andrew Lunn <andrew@...n.ch>, davem@...emloft.net,
        edumazet@...gle.com, pabeni@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, pengdonglin@...gfor.com.cn,
        huangcun@...gfor.com.cn
Subject: Re: [PATCH net-next] net: ethtool: Fix out-of-bounds copy to user

On 2023/6/6 2:39, Jakub Kicinski wrote:
> On Mon, 5 Jun 2023 11:39:59 +0800 Ding Hui wrote:
>> Case 1:
>> If the user len/n_stats is not zero, we will treat it as correct usage
>> (although we cannot distinguish between the real correct usage and
>> uninitialized usage). Return -EINVAL if current length exceed the one
>> user specified.
> 
> This assumes user will zero-initialize the value rather than do
> something like:
> 
> 	buf = malloc(1 << 16); // 64k should always be enough
> 	ioctl(s, ETHTOOL_GSTATS, buf)
> 
> 	for (i = 0; i < buf.n_stats; i++)
> 		/* use stats */
> 
> :(
> 

Sorry for late.

Now I'm not sure what can I do next besides reporting the issue.

>> Case 2:
>> If it is zero, we will treat it as incorrect usage, we can add a
>> pr_err_once() for it and keep to be compatible with it for a period of time.
>> At a suitable time in the future, this part can be removed by maintainers.
> 

-- 
Thanks,
- Ding Hui