[PATCH 3.12 041/155] can: add missing initialisations in CAN related skbuffs

[Jiri Slaby]

From: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>

3.12-stable 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>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 drivers/net/can/dev.c | 8 ++++++++
 net/can/af_can.c      | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index a4694aa20a3e..f66aeb79abdf 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -503,6 +503,14 @@ struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
 	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);
+
+	skb_reset_mac_header(skb);
+	skb_reset_network_header(skb);
+	skb_reset_transport_header(skb);
+
 	can_skb_reserve(skb);
 	can_skb_prv(skb)->ifindex = dev->ifindex;
 
diff --git a/net/can/af_can.c b/net/can/af_can.c
index ae3f07eb6cd7..5a668268f7ff 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -262,6 +262,9 @@ int can_send(struct sk_buff *skb, int loop)
 		goto inval_skb;
 	}
 
+	skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+	skb_reset_mac_header(skb);
 	skb_reset_network_header(skb);
 	skb_reset_transport_header(skb);
 
-- 
2.3.4

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