[SCSI] libsas: Fix potential NULL dereference in sas_smp_get_phy_events()

In sas_smp_get_phy_events() we never test if the call to
alloc_smp_req(RPEL_REQ_SIZE) succeeds or fails. That means we run
the risk of dereferencing a NULL pointer if it does fail. Far
better to test if we got NULL back and in that case return -ENOMEM
just as we already do for the other memory allocation in that
function.
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/libsas/sas_expander.c

@@ -507,14 +507,21 @@ static int sas_dev_present_in_domain(struct asd_sas_port *port,
 int sas_smp_get_phy_events(struct sas_phy *phy)
 {
 	int res;
+	u8 *req;
+	u8 *resp;
 	struct sas_rphy *rphy = dev_to_rphy(phy->dev.parent);
 	struct domain_device *dev = sas_find_dev_by_rphy(rphy);
-	u8 *req = alloc_smp_req(RPEL_REQ_SIZE);
-	u8 *resp = kzalloc(RPEL_RESP_SIZE, GFP_KERNEL);
 
-	if (!resp)
+	req = alloc_smp_req(RPEL_REQ_SIZE);
+	if (!req)
 		return -ENOMEM;
 
+	resp = alloc_smp_resp(RPEL_RESP_SIZE);
+	if (!resp) {
+		kfree(req);
+		return -ENOMEM;
+	}
+
 	req[1] = SMP_REPORT_PHY_ERR_LOG;
 	req[9] = phy->number;