linux-kernel - Re: [PATCH] scsi: ses: Fix out-of-bounds memory access in ses_enclosure_data

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Message-ID: <3385cf54-7b6c-3f28-e037-f0d4037368eb@redhat.com>
Date:   Mon, 20 May 2019 11:24:39 -0400
From:   Waiman Long <longman@...hat.com>
To:     James Bottomley <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] scsi: ses: Fix out-of-bounds memory access in
 ses_enclosure_data_process()

On 5/20/19 10:52 AM, James Bottomley wrote:
> On Mon, 2019-05-20 at 10:41 -0400, Waiman Long wrote:
> [...]
>>> --- a/drivers/scsi/ses.c
>>> +++ b/drivers/scsi/ses.c
>>> @@ -605,9 +605,14 @@ static void ses_enclosure_data_process(struct
>>> enclosure_device *edev,
>>>  			     /* these elements are optional */
>>>  			     type_ptr[0] ==
>>> ENCLOSURE_COMPONENT_SCSI_TARGET_PORT ||
>>>  			     type_ptr[0] ==
>>> ENCLOSURE_COMPONENT_SCSI_INITIATOR_PORT ||
>>> -			     type_ptr[0] ==
>>> ENCLOSURE_COMPONENT_CONTROLLER_ELECTRONICS))
>>> +			     type_ptr[0] ==
>>> ENCLOSURE_COMPONENT_CONTROLLER_ELECTRONICS)) {
>>>  				addl_desc_ptr += addl_desc_ptr[1]
>>> + 2;
>>>  
>>> +				/* Ensure no out-of-bounds memory
>>> access */
>>> +				if (addl_desc_ptr >= ses_dev-
>>>> page10 +
>>> +						     ses_dev-
>>>> page10_len)
>>> +					addl_desc_ptr = NULL;
>>> +			}
>>>  		}
>>>  	}
>>>  	kfree(buf);
>> Ping! Any comment on this patch.
> The update looks fine to me:
>
> Reviewed-by: James E.J. Bottomley <jejb@...ux.ibm.com>
>
> It might also be interesting to find out how the proliant is
> structuring this descriptor array to precipitate the out of bounds: Is
> it just an off by one or something more serious?

I didn't look into the detail the enclosure message returned by the
hardware, but I believe it may have more description entries (page7)
than extended description entries (page10).

I can try to reserve the system and find out what exactly is wrong with
that system if you really want to find that out.

Cheers,
Longman