2021-12-13 15:11:30

by George Kennedy

Subject: [PATCH RESEND] 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.

Reported-by: syzkaller <[email protected]>
Signed-off-by: George Kennedy <[email protected]>
---
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

2021-12-13 15:19:47

by Greg KH

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

On Mon, Dec 13, 2021 at 10:09:24AM -0500, George Kennedy wrote:
> 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.
>
> Reported-by: syzkaller <[email protected]>
> Signed-off-by: George Kennedy <[email protected]>
> ---
> drivers/ata/libata-scsi.c | 6 ++++++
> 1 file changed, 6 insertions(+)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>