Re: [PATCH RESEND 2] libata: if T_LENGTH is zero, dma direction should be DMA_NONE

[George Kennedy]

On 12/13/2021 4:37 PM, Damien Le Moal wrote:
> 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@xxxxxxxxxxxxxxx>  # 5.4.y
> 5.4 only ? What about other LTS versions ? They do not have that bug ?
Our distros are based on 5.4.y, 5.15.y and 4.14.y, so the fix should go 
there,
but it looks like the fix is also needed in: 5.14.y, 5.13.y, 5.10.y, and 
4.19.y.

Thank you,
George
> > Reported-by: syzkaller<syzkaller@xxxxxxxxxxxxxxxx>
> > Signed-off-by: George Kennedy<george.kennedy@xxxxxxxxxx>
> > ---
> >    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