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

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Date:   Mon, 14 Mar 2022 09:56:03 +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 Sat, 12 Mar 2022 01:25:38 +0800
Stephen Hemminger <stephen@...workplumber.org> wrote:

>> +	if (!pcpu_sum) {
>> +		for (j = 0; j < i; j++)
>> +			data[j] = 0;
>> +		return;
>> +	}
> 
> I don't think you understood what my comment was.
> 
> The zeroing here is not necessary. Just do:
>         if (!pcpu_sum)
>                return;
> 
> The data pointer is to buffer allocated here:
> 
> static int ethtool_get_stats(struct net_device *dev, void __user *useraddr)
> {
> ...
> 	if (n_stats) {
> 		data = vzalloc(array_size(n_stats, sizeof(u64)));  <<<<< is already zeroed.
> 		if (!data)
> 			return -ENOMEM;
> 		ops->get_ethtool_stats(dev, &stats, data);

OK, I will submit a v2 to remove them.

Jiang