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    Subject[PATCH 5.15 146/177] libata: if T_LENGTH is zero, dma direction should be DMA_NONE
    Date
    From: George Kennedy <george.kennedy@oracle.com>

    commit 5da5231bb47864e5dd6c6731151e98b6ee498827 upstream.

    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@vger.kernel.org>
    Reported-by: syzkaller<syzkaller@googlegroups.com>
    Signed-off-by: George Kennedy<george.kennedy@oracle.com>
    Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/ata/libata-scsi.c | 15 +++++++++++++--
    1 file changed, 13 insertions(+), 2 deletions(-)

    --- a/drivers/ata/libata-scsi.c
    +++ b/drivers/ata/libata-scsi.c
    @@ -2826,8 +2826,19 @@ static unsigned int ata_scsi_pass_thru(s
    goto invalid_fld;
    }

    - if (ata_is_ncq(tf->protocol) && (cdb[2 + cdb_offset] & 0x3) == 0)
    - tf->protocol = ATA_PROT_NCQ_NODATA;
    + if ((cdb[2 + cdb_offset] & 0x3) == 0) {
    + /*
    + * When T_LENGTH is zero (No data is transferred), dir should
    + * be DMA_NONE.
    + */
    + if (scmd->sc_data_direction != DMA_NONE) {
    + fp = 2 + cdb_offset;
    + goto invalid_fld;
    + }
    +
    + if (ata_is_ncq(tf->protocol))
    + tf->protocol = ATA_PROT_NCQ_NODATA;
    + }

    /* enable LBA */
    tf->flags |= ATA_TFLAG_LBA;

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