linux-kernel - [PATCH RESEND 2] libata: if T_LENGTH is zero, dma direction should be DMA

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Date:   Mon, 13 Dec 2021 10:33:51 -0500
From:   George Kennedy <george.kennedy@...cle.com>
To:     damien.lemoal@...nsource.wdc.com
Cc:     linux-ide@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        "GEORGE.KENNEDY" <george.kennedy@...cle.com>
Subject: [PATCH RESEND 2] libata: if T_LENGTH is zero, dma direction should be
 DMA_NONE

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@...r.kernel.org>  # 5.4.y
Reported-by: syzkaller<syzkaller@...glegroups.com>
Signed-off-by: George Kennedy<george.kennedy@...cle.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