[PATCH 3.4 086/172] can: add missing initialisations in CAN related skbuffs

[lizf]

From: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>

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

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


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>
[lizf: Backported to 3.4:
 - adjust context
 - drop changes to alloc_canfd_skb(), as there's no such function]
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
 drivers/net/can/dev.c | 5 +++++
 net/can/af_can.c      | 3 +++
 2 files changed, 8 insertions(+)

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 88c39e4..81a00e4 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -475,6 +475,11 @@ struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
 	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));
 
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 0ce2ad0..7d9dff222 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -244,6 +244,9 @@ int can_send(struct sk_buff *skb, int loop)
 	}
 
 	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);
 
-- 
1.9.1

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