linux-kernel - Re: [PATCH RESEND 2] libata: if T_LENGTH is zero, dma direction should be DMA

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Date:   Tue, 14 Dec 2021 06:37:29 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     George Kennedy <george.kennedy@...cle.com>
Cc:     linux-ide@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND 2] libata: if T_LENGTH is zero, dma direction
 should be DMA_NONE

On 2021/12/14 0:33, 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.
> 
> Cc:<stable@...r.kernel.org>  # 5.4.y

5.4 only ? What about other LTS versions ? They do not have that bug ?

> Reported-by: syzkaller<syzkaller@...glegroups.com>
> Signed-off-by: George Kennedy<george.kennedy@...cle.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
> 


-- 
Damien Le Moal
Western Digital Research