softraid.c: potential NULL pointer dereference ?

[Remco]

I noticed the following code path in /sys/dev/softraid.c:

int
sr_scsi_cmd(struct scsi_xfer *xs)
{
...
        sd = sc->sc_dis[link->scsibus];
        if (sd == NULL) {
                s = splhigh();
                sd = sc->sc_attach_dis;
                splx(s);

                DNPRINTF(SR_D_CMD, "%s: sr_scsi_cmd: attaching %p\n",
                    DEVNAME(sc), sd);
                if (sd == NULL) {
                        wu = NULL;
                        printf("%s: sr_scsi_cmd NULL discipline\n",
                            DEVNAME(sc));
                        goto stuffup;
...
stuffup:
        if (sd->sd_scsi_sense.error_code) {


If I'm not mistaken this leads to dereferencing sd as a NULL pointer.

I'm not sure whether this causes an actual real world problem or where to put 
a guard to avoid this.


Regards,
Remco