linux-kernel - Re: [PATCH] scsi: Let scsi_execute_cmd() mark args->sshdr as invalid

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Message-ID: <ffb8237c-bd38-e323-0179-4313d9ef0a75@oracle.com>
Date:   Mon, 22 May 2023 16:54:30 +0100
From:   John Garry <john.g.garry@...cle.com>
To:     Bart Van Assche <bvanassche@....org>,
        Juergen Gross <jgross@...e.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>, stable@...r.kernel.org
Subject: Re: [PATCH] scsi: Let scsi_execute_cmd() mark args->sshdr as invalid

On 22/05/2023 14:31, Bart Van Assche wrote:
> On 5/22/23 02:55, John Garry wrote:
>> On 19/05/2023 18:39, Bart Van Assche wrote:
>>>        *args->resid = scmd->resid_len;
>>> -    if (args->sense)
>>> -        memcpy(args->sense, scmd->sense_buffer, SCSI_SENSE_BUFFERSIZE);
>>> +    if (args->sense) {
>>> +        *args->sense = scmd->sense_buffer;
>>> +        scmd->sense_buffer = NULL;
>>
>> I think that you will agree that this is not a good pattern to follow. 
>> We cannot have SCSI core allocating the sense buffer but a driver 
>> freeing it.
> 
> Why not? Something similar can happen anywhere in the kernel anywhere 
> reference counting is used.

Sure, but you are not using ref counting. If you could use ref counting 
then it would be better.

Thanks,
John