net: hsr: fix mac_len checks

Commit 2e9f60932a2c ("net: hsr: check skb can contain struct hsr_ethhdr
in fill_frame_info") added the following which resulted in -EINVAL
always being returned:
	if (skb->mac_len < sizeof(struct hsr_ethhdr))
		return -EINVAL;

mac_len was not being set correctly so this check completely broke
HSR/PRP since it was always 14, not 20.

Set mac_len correctly and modify the mac_len checks to test in the
correct places since sometimes it is legitimately 14.

Fixes: 2e9f60932a2c ("net: hsr: check skb can contain struct hsr_ethhdr in fill_frame_info")
Signed-off-by: George McCollister <george.mccollister@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 21 insertions, 9 deletions

diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c
index 6852e9bccf5b..ceb8afb2a62f 100644
--- a/net/hsr/hsr_forward.c
+++ b/net/hsr/hsr_forward.c
@@ -474,8 +474,8 @@ static void handle_std_frame(struct sk_buff *skb,
 	}
 }
 
-void hsr_fill_frame_info(__be16 proto, struct sk_buff *skb,
-			 struct hsr_frame_info *frame)
+int hsr_fill_frame_info(__be16 proto, struct sk_buff *skb,
+			struct hsr_frame_info *frame)
 {
 	struct hsr_port *port = frame->port_rcv;
 	struct hsr_priv *hsr = port->hsr;
@@ -483,20 +483,26 @@ void hsr_fill_frame_info(__be16 proto, struct sk_buff *skb,
 	/* HSRv0 supervisory frames double as a tag so treat them as tagged. */
 	if ((!hsr->prot_version && proto == htons(ETH_P_PRP)) ||
 	    proto == htons(ETH_P_HSR)) {
+		/* Check if skb contains hsr_ethhdr */
+		if (skb->mac_len < sizeof(struct hsr_ethhdr))
+			return -EINVAL;
+
 		/* HSR tagged frame :- Data or Supervision */
 		frame->skb_std = NULL;
 		frame->skb_prp = NULL;
 		frame->skb_hsr = skb;
 		frame->sequence_nr = hsr_get_skb_sequence_nr(skb);
-		return;
+		return 0;
 	}
 
 	/* Standard frame or PRP from master port */
 	handle_std_frame(skb, frame);
+
+	return 0;
 }
 
-void prp_fill_frame_info(__be16 proto, struct sk_buff *skb,
-			 struct hsr_frame_info *frame)
+int prp_fill_frame_info(__be16 proto, struct sk_buff *skb,
+			struct hsr_frame_info *frame)
 {
 	/* Supervision frame */
 	struct prp_rct *rct = skb_get_PRP_rct(skb);
@@ -507,9 +513,11 @@ void prp_fill_frame_info(__be16 proto, struct sk_buff *skb,
 		frame->skb_std = NULL;
 		frame->skb_prp = skb;
 		frame->sequence_nr = prp_get_skb_sequence_nr(rct);
-		return;
+		return 0;
 	}
 	handle_std_frame(skb, frame);
+
+	return 0;
 }
 
 static int fill_frame_info(struct hsr_frame_info *frame,
@@ -519,9 +527,10 @@ static int fill_frame_info(struct hsr_frame_info *frame,
 	struct hsr_vlan_ethhdr *vlan_hdr;
 	struct ethhdr *ethhdr;
 	__be16 proto;
+	int ret;
 
-	/* Check if skb contains hsr_ethhdr */
-	if (skb->mac_len < sizeof(struct hsr_ethhdr))
+	/* Check if skb contains ethhdr */
+	if (skb->mac_len < sizeof(struct ethhdr))
 		return -EINVAL;
 
 	memset(frame, 0, sizeof(*frame));
@@ -548,7 +557,10 @@ static int fill_frame_info(struct hsr_frame_info *frame,
 
 	frame->is_from_san = false;
 	frame->port_rcv = port;
-	hsr->proto_ops->fill_frame_info(proto, skb, frame);
+	ret = hsr->proto_ops->fill_frame_info(proto, skb, frame);
+	if (ret)
+		return ret;
+
 	check_local_dest(port->hsr, skb, frame);
 
 	return 0;