On 12/13/2021 4:37 PM, Damien Le Moal wrote:

On 2021/12/14 0:33, George Kennedy wrote:

quoted

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:[off-list ref]  # 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

quoted

Reported-by: syzkaller<redacted>
Signed-off-by: George Kennedy<redacted>
---
   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