linux-kernel - Re: [PATCH] IB/srpt: Fix passing zero to 'PTR

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Date:   Fri, 14 May 2021 15:54:18 +0800
From:   YueHaibing <yuehaibing@...wei.com>
To:     Jason Gunthorpe <jgg@...dia.com>,
        Bart Van Assche <bvanassche@....org>
CC:     <dledford@...hat.com>, <linux-rdma@...r.kernel.org>,
        <target-devel@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] IB/srpt: Fix passing zero to 'PTR_ERR'

On 2020/11/13 2:30, Jason Gunthorpe wrote:
> On Thu, Nov 12, 2020 at 10:25:48AM -0800, Bart Van Assche wrote:
>> On 11/12/20 9:20 AM, Jason Gunthorpe wrote:
>>> I think it should be like this, Bart?
>>>
>>> diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
>>> index 6017d525084a0c..80f9673956ced2 100644
>>> +++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
>>> @@ -2311,7 +2311,7 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
>>>   	mutex_lock(&sport->port_guid_id.mutex);
>>>   	list_for_each_entry(stpg, &sport->port_guid_id.tpg_list, entry) {
>>> -		if (!IS_ERR_OR_NULL(ch->sess))
>>> +		if (ch->sess)
>>>   			break;
>>>   		ch->sess = target_setup_session(&stpg->tpg, tag_num,
>>>   						tag_size, TARGET_PROT_NORMAL,
>>> @@ -2321,12 +2321,12 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
>>>   	mutex_lock(&sport->port_gid_id.mutex);
>>>   	list_for_each_entry(stpg, &sport->port_gid_id.tpg_list, entry) {
>>> -		if (!IS_ERR_OR_NULL(ch->sess))
>>> +		if (ch->sess)
>>>   			break;
>>>   		ch->sess = target_setup_session(&stpg->tpg, tag_num,
>>>   					tag_size, TARGET_PROT_NORMAL, i_port_id,
>>>   					ch, NULL);
>>> -		if (!IS_ERR_OR_NULL(ch->sess))
>>> +		if (ch->sess)
>>>   			break;
>>>   		/* Retry without leading "0x" */
>>>   		ch->sess = target_setup_session(&stpg->tpg, tag_num,
>>> @@ -2335,7 +2335,9 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
>>>   	}
>>>   	mutex_unlock(&sport->port_gid_id.mutex);
>>> -	if (IS_ERR_OR_NULL(ch->sess)) {
>>> +	if (!ch->sess)
>>> +		ch->sess = ERR_PTR(-ENOENT);
>>> +	if (IS_ERR(ch->sess)) {
>>>   		WARN_ON_ONCE(ch->sess == NULL);
>>>   		ret = PTR_ERR(ch->sess);
>>>   		ch->sess = NULL;
>>>
>>
>> Hi Jason,
>>
>> The ib_srpt driver accepts three different formats for the initiator ACL. Up
>> to two of the three target_setup_session() calls will fail if the fifth
>> argument of target_setup_session() does not use the format of the initiator
>> ID in configfs. If the first or the second target_setup_session() call fails
>> it is essential that later target_setup_session() calls happen. Hence the
>> IS_ERR_OR_NULL(ch->sess) checks in the above loops.
> 
> IS_ERR_OR_NULL is an abomination, it should not be used.
> 
> I see I didn't quite get it right, but that is still closer to sane,
> probably target_setup_session() should return NULL not err_ptr

Any fix plan?

> 
> Jason
> .
>