scsi: fcoe: Embed fc_rport_priv in fcoe_rport structure

BugLink: https://bugs.launchpad.net/bugs/1845038

commit 023358b1 upstream.

Gcc-9 complains for a memset across pointer boundaries, which happens as
the code tries to allocate a flexible array on the stack.  Turns out we
cannot do this without relying on gcc-isms, so with this patch we'll embed
the fc_rport_priv structure into fcoe_rport, can use the normal
'container_of' outcast, and will only have to do a memset over one
structure.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/scsi/fcoe/fcoe_ctlr.c

@@ -1973,7 +1973,7 @@ EXPORT_SYMBOL_GPL(fcoe_wwn_from_mac);
  */
 static inline struct fcoe_rport *fcoe_ctlr_rport(struct fc_rport_priv *rdata)
 {
-	return (struct fcoe_rport *)(rdata + 1);
+	return container_of(rdata, struct fcoe_rport, rdata);
 }
 
 /**
@@ -2233,7 +2233,7 @@ static void fcoe_ctlr_vn_start(struct fcoe_ctlr *fip)
  */
 static int fcoe_ctlr_vn_parse(struct fcoe_ctlr *fip,
 			      struct sk_buff *skb,
-			      struct fc_rport_priv *rdata)
+			      struct fcoe_rport *frport)
 {
 	struct fip_header *fiph;
 	struct fip_desc *desc = NULL;
@@ -2241,16 +2241,12 @@ static int fcoe_ctlr_vn_parse(struct fcoe_ctlr *fip,
 	struct fip_wwn_desc *wwn = NULL;
 	struct fip_vn_desc *vn = NULL;
 	struct fip_size_desc *size = NULL;
-	struct fcoe_rport *frport;
 	size_t rlen;
 	size_t dlen;
 	u32 desc_mask = 0;
 	u32 dtype;
 	u8 sub;
 
-	memset(rdata, 0, sizeof(*rdata) + sizeof(*frport));
-	frport = fcoe_ctlr_rport(rdata);
-
 	fiph = (struct fip_header *)skb->data;
 	frport->flags = ntohs(fiph->fip_flags);
 
@@ -2313,15 +2309,17 @@ static int fcoe_ctlr_vn_parse(struct fcoe_ctlr *fip,
 			if (dlen != sizeof(struct fip_wwn_desc))
 				goto len_err;
 			wwn = (struct fip_wwn_desc *)desc;
-			rdata->ids.node_name = get_unaligned_be64(&wwn->fd_wwn);
+			frport->rdata.ids.node_name =
+				get_unaligned_be64(&wwn->fd_wwn);
 			break;
 		case FIP_DT_VN_ID:
 			if (dlen != sizeof(struct fip_vn_desc))
 				goto len_err;
 			vn = (struct fip_vn_desc *)desc;
 			memcpy(frport->vn_mac, vn->fd_mac, ETH_ALEN);
-			rdata->ids.port_id = ntoh24(vn->fd_fc_id);
-			rdata->ids.port_name = get_unaligned_be64(&vn->fd_wwpn);
+			frport->rdata.ids.port_id = ntoh24(vn->fd_fc_id);
+			frport->rdata.ids.port_name =
+				get_unaligned_be64(&vn->fd_wwpn);
 			break;
 		case FIP_DT_FC4F:
 			if (dlen != sizeof(struct fip_fc4_feat))
@@ -2664,16 +2662,13 @@ static int fcoe_ctlr_vn_recv(struct fcoe_ctlr *fip, struct sk_buff *skb)
 {
 	struct fip_header *fiph;
 	enum fip_vn2vn_subcode sub;
-	struct {
-		struct fc_rport_priv rdata;
-		struct fcoe_rport frport;
-	} buf;
+	struct fcoe_rport frport = { };
 	int rc;
 
 	fiph = (struct fip_header *)skb->data;
 	sub = fiph->fip_subcode;
 
-	rc = fcoe_ctlr_vn_parse(fip, skb, &buf.rdata);
+	rc = fcoe_ctlr_vn_parse(fip, skb, &frport);
 	if (rc) {
 		LIBFCOE_FIP_DBG(fip, "vn_recv vn_parse error %d\n", rc);
 		goto drop;
@@ -2682,19 +2677,19 @@ static int fcoe_ctlr_vn_recv(struct fcoe_ctlr *fip, struct sk_buff *skb)
 	mutex_lock(&fip->ctlr_mutex);
 	switch (sub) {
 	case FIP_SC_VN_PROBE_REQ:
-		fcoe_ctlr_vn_probe_req(fip, &buf.rdata);
+		fcoe_ctlr_vn_probe_req(fip, &frport.rdata);
 		break;
 	case FIP_SC_VN_PROBE_REP:
-		fcoe_ctlr_vn_probe_reply(fip, &buf.rdata);
+		fcoe_ctlr_vn_probe_reply(fip, &frport.rdata);
 		break;
 	case FIP_SC_VN_CLAIM_NOTIFY:
-		fcoe_ctlr_vn_claim_notify(fip, &buf.rdata);
+		fcoe_ctlr_vn_claim_notify(fip, &frport.rdata);
 		break;
 	case FIP_SC_VN_CLAIM_REP:
-		fcoe_ctlr_vn_claim_resp(fip, &buf.rdata);
+		fcoe_ctlr_vn_claim_resp(fip, &frport.rdata);
 		break;
 	case FIP_SC_VN_BEACON:
-		fcoe_ctlr_vn_beacon(fip, &buf.rdata);
+		fcoe_ctlr_vn_beacon(fip, &frport.rdata);
 		break;
 	default:
 		LIBFCOE_FIP_DBG(fip, "vn_recv unknown subcode %d\n", sub);

drivers/scsi/libfc/fc_rport.c

@@ -121,12 +121,15 @@ static struct fc_rport_priv *fc_rport_create(struct fc_lport *lport,
 					     u32 port_id)
 {
 	struct fc_rport_priv *rdata;
+	size_t rport_priv_size = sizeof(*rdata);
 
 	rdata = lport->tt.rport_lookup(lport, port_id);
 	if (rdata)
 		return rdata;
 
-	rdata = kzalloc(sizeof(*rdata) + lport->rport_priv_size, GFP_KERNEL);
+	if (lport->rport_priv_size > 0)
+		rport_priv_size = lport->rport_priv_size;
+	rdata = kzalloc(rport_priv_size, GFP_KERNEL);
 	if (!rdata)
 		return NULL;
 

include/scsi/libfcoe.h

@@ -236,6 +236,7 @@ struct fcoe_fcf {
  * @vn_mac:	VN_Node assigned MAC address for data
  */
 struct fcoe_rport {
+	struct fc_rport_priv rdata;
 	unsigned long time;
 	u16 fcoe_len;
 	u16 flags;