[PATCH 5.4 52/71] libata: if T_LENGTH is zero, dma direction should be DMA_NONE

[Greg Kroah-Hartman]

From: George Kennedy <george.kennedy@xxxxxxxxxx>

commit 5da5231bb47864e5dd6c6731151e98b6ee498827 upstream.

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>
Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/ata/libata-scsi.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3164,8 +3164,19 @@ static unsigned int ata_scsi_pass_thru(s
 		goto invalid_fld;
 	}
 
-	if (ata_is_ncq(tf->protocol) && (cdb[2 + cdb_offset] & 0x3) == 0)
-		tf->protocol = ATA_PROT_NCQ_NODATA;
+	if ((cdb[2 + cdb_offset] & 0x3) == 0) {
+		/*
+		 * When T_LENGTH is zero (No data is transferred), dir should
+		 * be DMA_NONE.
+		 */
+		if (scmd->sc_data_direction != DMA_NONE) {
+			fp = 2 + cdb_offset;
+			goto invalid_fld;
+		}
+
+		if (ata_is_ncq(tf->protocol))
+			tf->protocol = ATA_PROT_NCQ_NODATA;
+	}
 
 	/* enable LBA */
 	tf->flags |= ATA_TFLAG_LBA;