[PATCH 4.14 30/45] libata: if T_LENGTH is zero, dma direction should be DMA_NONE

Greg Kroah-Hartman
2021-12-20T14:40:59Z

From: George Kennedy <george.kennedy@oracle.com>

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@vger.kernel.org>
Reported-by: syzkaller<syzkaller@googlegroups.com>
Signed-off-by: George Kennedy<george.kennedy@oracle.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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
@@ -3182,8 +3182,19 @@ 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;