linux-kernel - Re: [PATH v2] scsi: scsi_dh_rdac: Avoid crash during rdac_bus

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Message-ID: <61016887.9000200@huawei.com>
Date:   Wed, 28 Jul 2021 22:24:07 +0800
From:   yebin <yebin10@...wei.com>
To:     Bart Van Assche <bvanassche@....org>, <jejb@...ux.ibm.com>,
        <martin.petersen@...cle.com>, <linux-scsi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATH v2] scsi: scsi_dh_rdac: Avoid crash during rdac_bus_attach



On 2021/7/23 12:04, Bart Van Assche wrote:
> On 1/12/21 10:31 PM, Ye Bin wrote:
>>   	sdev->handler_data = NULL;
>> +	synchronize_rcu();
>>   	kfree(h);
> What is the purpose of the new synchronize_rcu() call?
Thanks for your reply.
Yes, I add new synchronize_rcu() call is to wait until *h is no longer 
in use. If free
"h" right now , mybe lead to UAF.
> If its purpose is
> to wait until *h is no longer in use, please use kfree_rcu() instead.
struct rdac_dh_data {
         struct list_head        node;
         .....
}
As rdac_dh_data.node type is "struct list_head", but  kfree_rcu the 
first parameter type is
"struct rcu_head". So we can only use synchronize_rcu() at here.
>
> Thanks,
>
> Bart.
> .
>