[PATCH 3.2 114/221] can: add missing initialisations in CAN related skbuffs

[Ben Hutchings]

3.2.69-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>

commit 969439016d2cf61fef53a973d7e6d2061c3793b1 upstream.

When accessing CAN network interfaces with AF_PACKET sockets e.g. by dhclient
this can lead to a skb_under_panic due to missing skb initialisations.

Add the missing initialisations at the CAN skbuff creation times on driver
level (rx path) and in the network layer (tx path).

Reported-by: Austin Schuh <austin@xxxxxxxxxxxxxxxx>
Reported-by: Daniel Steer <daniel.steer@xxxxxxxxxxx>
Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
[bwh: Backported to 3.2:
 - Adjust context
 - Drop changes to alloc_canfd_skb()]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -468,6 +468,11 @@ struct sk_buff *alloc_can_skb(struct net
 	skb->protocol = htons(ETH_P_CAN);
 	skb->pkt_type = PACKET_BROADCAST;
 	skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+	skb_reset_mac_header(skb);
+	skb_reset_network_header(skb);
+	skb_reset_transport_header(skb);
+
 	*cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
 	memset(*cf, 0, sizeof(struct can_frame));
 
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -244,6 +244,9 @@ int can_send(struct sk_buff *skb, int lo
 	}
 
 	skb->protocol = htons(ETH_P_CAN);
+	skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+	skb_reset_mac_header(skb);
 	skb_reset_network_header(skb);
 	skb_reset_transport_header(skb);
 

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