linux-kernel - Re: [PATCH] hv_netvsc: Add check for kvmalloc

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Date:   Fri, 11 Mar 2022 11:20:59 +0800
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     stephen@...workplumber.org
Cc:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        wei.liu@...nel.org, decui@...rosoft.com, davem@...emloft.net,
        kuba@...nel.org, ast@...nel.org, daniel@...earbox.net,
        hawk@...nel.org, john.fastabend@...il.com, andrii@...nel.org,
        kafai@...com, songliubraving@...com, yhs@...com,
        kpsingh@...nel.org, linux-hyperv@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        bpf@...r.kernel.org, Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: Re: [PATCH] hv_netvsc: Add check for kvmalloc_array

On Fri, 11 Mar 2022 11:00:24 +0800
Stephen Hemminger <stephen@...workplumber.org> wrote:
>> +	if (!pcpu_sum) {
>> +		for (j = 0; j < i; j++)
>> +			data[j] = 0;
>> +		return
> 
> Why is unrolled zero (memset) needed? The data area comes from
> ethtool_get_stats and is already zeroed (vzalloc).
> 
> 
> There does look like at TOCTOU error here with on the number of stats.
> Code doesn't look hotplug safe.
> Not sure, but that issue might have been raised during review.

I unrolled the 'data area' since the three 'for loops' before
have already assigned the value to the data area.
And I have not found any review about it.

Thanks,
Jiang