scsi: sg: fix SG_DXFER_FROM_DEV transfers

SG_DXFER_FROM_DEV transfers do not necessarily have a dxferp as we set
it to NULL for the old sg_io read/write interface, but must have a
length bigger than 0. This fixes a regression introduced by commit
28676d869bbb ("scsi: sg: check for valid direction before starting the
request")

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Fixes: 28676d869bbb ("scsi: sg: check for valid direction before starting the request")
Reported-by: Chris Clayton <chris2553@googlemail.com>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 21225d62b0c1f4424bc72f57f8daf109cabffb7e..1e82d4128a84800d3f96011c49e0b3fc12c55d8e 100644 (file)
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -758,8 +758,11 @@ static bool sg_is_valid_dxfer(sg_io_hdr_t *hp)
                if (hp->dxferp || hp->dxfer_len > 0)
                        return false;
                return true;
-       case SG_DXFER_TO_DEV:
        case SG_DXFER_FROM_DEV:
+               if (hp->dxfer_len < 0)
+                       return false;
+               return true;
+       case SG_DXFER_TO_DEV:
        case SG_DXFER_TO_FROM_DEV:
                if (!hp->dxferp || hp->dxfer_len == 0)
                        return false;