Packets with pkt_type == PACKET_LOOPBACK are captured by
handle_frame() function, but they don't have L2 header.
We should not process them in handle_mode_l2().

This doesn't affect old L2 functionality, since handling
was anyway incorrect.

Handle them the same way as in br_handle_frame():
just pass the skb.

To observe invalid behaviour, just start "ping -b" on bcast address
of port-interface.

Signed-off-by: Dmitry Skorodumov <redacted>
---
 drivers/net/ipvlan/ipvlan_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ipvlan/ipvlan_core.c b/drivers/net/ipvlan/ipvlan_core.c
index ce6202667159..ba2bea5f0a1a 100644
--- a/drivers/net/ipvlan/ipvlan_core.c
+++ b/drivers/net/ipvlan/ipvlan_core.c

@@ -1157,6 +1157,9 @@ static rx_handler_result_t ipvlan_handle_mode_l2(struct sk_buff **pskb,
 	struct sk_buff *skb = *pskb;
 	bool need_eth_fix;
 
+	if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
+		return RX_HANDLER_PASS;
+
 	/* Ignore already seen packets. */
 	if (ipvlan_is_skb_marked(skb, port->dev))
 		return RX_HANDLER_PASS;

-- 
2.25.1