linux-kernel - [PATCH net-next v4 4/5] net: hdlc_fr: Do skb_reset_mac_header for skbs received on normal PVC devices

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Date:   Thu, 29 Oct 2020 19:28:38 -0700
From:   Xie He <xie.he.0141@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Krzysztof Halasa <khc@...waw.pl>
Cc:     Xie He <xie.he.0141@...il.com>
Subject: [PATCH net-next v4 4/5] net: hdlc_fr: Do skb_reset_mac_header for skbs received on normal PVC devices

When an skb is received on a normal (non-Ethernet-emulating) PVC device,
call skb_reset_mac_header before we pass it to upper layers.

This is because normal PVC devices don't have header_ops, so any header we
have would not be visible to upper layer code when sending, so the header
shouldn't be visible to upper layer code when receiving, either.

Cc: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: Krzysztof Halasa <khc@...waw.pl>
Signed-off-by: Xie He <xie.he.0141@...il.com>
---
 drivers/net/wan/hdlc_fr.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c
index 3639c2bfb141..9a37575686b9 100644
--- a/drivers/net/wan/hdlc_fr.c
+++ b/drivers/net/wan/hdlc_fr.c
@@ -935,6 +935,7 @@ static int fr_rx(struct sk_buff *skb)
 		skb_pull(skb, 4); /* Remove 4-byte header (hdr, UI, NLPID) */
 		skb->dev = pvc->main;
 		skb->protocol = htons(ETH_P_IP);
+		skb_reset_mac_header(skb);
 
 	} else if (data[3] == NLPID_IPV6) {
 		if (!pvc->main)
@@ -942,6 +943,7 @@ static int fr_rx(struct sk_buff *skb)
 		skb_pull(skb, 4); /* Remove 4-byte header (hdr, UI, NLPID) */
 		skb->dev = pvc->main;
 		skb->protocol = htons(ETH_P_IPV6);
+		skb_reset_mac_header(skb);
 
 	} else if (skb->len > 10 && data[3] == FR_PAD &&
 		   data[4] == NLPID_SNAP && data[5] == FR_PAD) {
@@ -958,6 +960,7 @@ static int fr_rx(struct sk_buff *skb)
 				goto rx_drop;
 			skb->dev = pvc->main;
 			skb->protocol = htons(pid);
+			skb_reset_mac_header(skb);
 			break;
 
 		case 0x80C20007: /* bridged Ethernet frame */
-- 
2.27.0