[SCSI] ch: Check NULL for kmalloc() return

Verify that ch->dt is not NULL before using it.
Signed-off-by: Davidlohr Bueso <dave@gnu.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/ch.c

@@ -353,6 +353,12 @@ ch_readconfig(scsi_changer *ch)
 	/* look up the devices of the data transfer elements */
 	ch->dt = kmalloc(ch->counts[CHET_DT]*sizeof(struct scsi_device),
 			 GFP_KERNEL);
+
+	if (!ch->dt) {
+		kfree(buffer);
+		return -ENOMEM;
+	}
+
 	for (elem = 0; elem < ch->counts[CHET_DT]; elem++) {
 		id  = -1;
 		lun = 0;