Re: [PATCH RESEND 2] libata: if T_LENGTH is zero, dma direction should be DMA_NONE

[George Kennedy <george.kennedy@oracle.com>]

On 12/13/2021 4:37 PM, Damien Le Moal wrote:
> On 2021/12/14 0:33, George Kennedy wrote:
>> Avoid data corruption by rejecting pass-through commands where
>> T_LENGTH is zero (No data is transferred) and the dma direction
>> is not DMA_NONE.
>>
>> Cc:<stable@vger.kernel.org>  # 5.4.y
> 5.4 only ? What about other LTS versions ? They do not have that bug ?
Our distros are based on 5.4.y, 5.15.y and 4.14.y, so the fix should go 
there,
but it looks like the fix is also needed in: 5.14.y, 5.13.y, 5.10.y, and 
4.19.y.

Thank you,
George
>
>> Reported-by: syzkaller<syzkaller@googlegroups.com>
>> Signed-off-by: George Kennedy<george.kennedy@oracle.com>
>> ---
>>    drivers/ata/libata-scsi.c | 6 ++++++
>>    1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
>> index 1b84d55..d428392 100644
>> --- a/drivers/ata/libata-scsi.c
>> +++ b/drivers/ata/libata-scsi.c
>> @@ -2859,6 +2859,12 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
>>    		goto invalid_fld;
>>    	}
>>    
>> +	/* if T_LENGTH is zero (No data is transferred), then dir should be DMA_NONE */
>> +	if ((cdb[2 + cdb_offset] & 3) == 0 && scmd->sc_data_direction != DMA_NONE) {
>> +		fp = 2 + cdb_offset;
>> +		goto invalid_fld;
>> +	}
>> +
>>    	if (ata_is_ncq(tf->protocol) && (cdb[2 + cdb_offset] & 0x3) == 0)
>>    		tf->protocol = ATA_PROT_NCQ_NODATA;
>>    
>> -- 1.8.3.1
>>
>