2021-12-09 15:02:28

by George Kennedy

Subject: [PATCH] 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

2021-12-09 15:10:16

by Greg KH

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

On Thu, Dec 09, 2021 at 10:00:20AM -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(+)
>
> 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
>

Odd, why send this to me?

Also, you should look at:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to send patches to automatically get included in stable
releases, which is what I think you want here.

thanks,

greg k-h