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

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

[George Kennedy]

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 <syzkaller@googlegroups.com>
Signed-off-by: George Kennedy <george.kennedy@oracle.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

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

[Greg KH]

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 <syzkaller@googlegroups.com>
> Signed-off-by: George Kennedy <george.kennedy@oracle.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
> 

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