linux-hardening - Re: [PATCH v3][next] scsi: smartpqi: Replace one-element array with flexible-array member

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Date:   Tue, 7 Feb 2023 17:09:06 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Kees Cook <keescook@...omium.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc:     Don Brace <don.brace@...rochip.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        storagedev@...rochip.com, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v3][next] scsi: smartpqi: Replace one-element array with
 flexible-array member



On 2/7/23 17:01, Kees Cook wrote:
> On Tue, Feb 07, 2023 at 03:59:43PM -0600, Gustavo A. R. Silva wrote:
>> One-element arrays are deprecated, and we are replacing them with flexible
>> array members instead. So, replace one-element array with flexible-array
>> member in struct report_log_lun_list.
>>
>> This helps with the ongoing efforts to tighten the FORTIFY_SOURCE routines
>> on memcpy().
>>
>> Link: https://github.com/KSPP/linux/issues/79
>> Link: https://github.com/KSPP/linux/issues/204
>> Acked-by: Don Brace <don.brace@...rochip.com>
>> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> 
> Looks good to me -- both before and after, there is 1 extra all-zero
> entry at the end. But now the struct is using a flex array correctly.

Yep. :)

> 
> Reviewed-by: Kees Cook <keescook@...omium.org>

Thanks!
--
Gustavo

> 
> -Kees
> 
>> ---
>> Changes in v3:
>>   - Amplify the existing comment instead of adding a new one. By Don
>>     Brace[1].
>>   - Add Don's Acked-by tag to the changelog.
>>     Link: https://lore.kernel.org/linux-hardening/d881ad98-a291-1c9b-53dc-199f23f1625e@embeddedor.com/ [1]
>>
>> Changes in v2:
>>   - In v1 we thought that the original code was allocating one too-many
>>     entries for the list. However, Don Brace commented that the allocation
>>     was actually intentional[2]. So, I added a code comment with his feedback.
>>     Link: https://lore.kernel.org/linux-hardening/16e6c434-44af-2efb-d4bc-a253e93e5590@embeddedor.com/  [2]
>>
>> v1:
>>   - Link: https://lore.kernel.org/linux-hardening/c80c0979933e0c05e80d95792ef167a28640a14b.1663816572.git.gustavoars@kernel.org/
>>
>>   drivers/scsi/smartpqi/smartpqi.h      | 2 +-
>>   drivers/scsi/smartpqi/smartpqi_init.c | 3 ++-
>>   2 files changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/scsi/smartpqi/smartpqi.h b/drivers/scsi/smartpqi/smartpqi.h
>> index af27bb0f3133..228838eb3686 100644
>> --- a/drivers/scsi/smartpqi/smartpqi.h
>> +++ b/drivers/scsi/smartpqi/smartpqi.h
>> @@ -954,7 +954,7 @@ struct report_log_lun {
>>   
>>   struct report_log_lun_list {
>>   	struct report_lun_header header;
>> -	struct report_log_lun lun_entries[1];
>> +	struct report_log_lun lun_entries[];
>>   };
>>   
>>   struct report_phys_lun_8byte_wwid {
>> diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
>> index d0446d4d4465..49a8f91810b6 100644
>> --- a/drivers/scsi/smartpqi/smartpqi_init.c
>> +++ b/drivers/scsi/smartpqi/smartpqi_init.c
>> @@ -1259,7 +1259,8 @@ static int pqi_get_device_lists(struct pqi_ctrl_info *ctrl_info,
>>   			"report logical LUNs failed\n");
>>   
>>   	/*
>> -	 * Tack the controller itself onto the end of the logical device list.
>> +	 * Tack the controller itself onto the end of the logical device list
>> +	 * by adding a list entry that is all zeros.
>>   	 */
>>   
>>   	logdev_data = *logdev_list;
>> -- 
>> 2.34.1
>>
>