[PATCH RESEND 3] libata: if T_LENGTH is zero, dma direction should be DMA_NONE

[George Kennedy <george.kennedy@xxxxxxxxxx>]

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@xxxxxxxxxxxxxxx>
Reported-by: syzkaller<syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: George Kennedy<george.kennedy@xxxxxxxxxx>
---
 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