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Subject: Re: [RFC PATCH 15/15] drivers/acrn: add the support of offline SOS
 cpu
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org,
        Jason Chen CJ <jason.cj.chen@intel.com>
References: <1565922356-4488-1-git-send-email-yakui.zhao@intel.com>
 <1565922356-4488-16-git-send-email-yakui.zhao@intel.com>
 <20190819103417.GD4451@kadam>
From:   "Zhao, Yakui" <yakui.zhao@intel.com>
Message-ID: <18360e11-22af-8f14-21ad-3fa0e8d23210@intel.com>
Date:   Tue, 20 Aug 2019 10:23:14 +0800
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On 2019年08月19日 18:34, Dan Carpenter wrote:
> On Fri, Aug 16, 2019 at 10:25:56AM +0800, Zhao Yakui wrote:
>> diff --git a/drivers/staging/acrn/acrn_dev.c b/drivers/staging/acrn/acrn_dev.c
>> index 0602125..6868003 100644
>> --- a/drivers/staging/acrn/acrn_dev.c
>> +++ b/drivers/staging/acrn/acrn_dev.c
>> @@ -588,6 +588,41 @@ static const struct file_operations fops = {
>>   #define SUPPORT_HV_API_VERSION_MAJOR	1
>>   #define SUPPORT_HV_API_VERSION_MINOR	0
>>   
>> +static ssize_t
>> +offline_cpu_store(struct device *dev,
>> +			struct device_attribute *attr,
>> +			const char *buf, size_t count)
>> +{
>> +#ifdef CONFIG_X86
>> +	u64 cpu, lapicid;
>> +
>> +	if (kstrtoull(buf, 0, &cpu) < 0)
>> +		return -EINVAL;
> 

Thanks for the review.

Make sense.
The error code will be preserved.

> Preserve the error code.
> 
> 	ret = kstrtoull(buf, 0, &cpu);
> 	if (ret)
> 		return ret;


> 
>> +
>> +	if (cpu_possible(cpu)) {
> 
> You can't pass unchecked cpu values to cpu_possible() or it results in
> an out of bounds read if cpu is >= than nr_cpu_ids.
> 

OK. It will add the check of "cpu < num_possibles_cpu()" to avoid the 
out of bounds.

> regards,
> dan carpenter
>