Each net_device in a system will automatically managed as a possible
batman_if and holds different informations like a buffer with a prepared
originator messages. To reduce the memory usage, the packet_buff will
only be allocated when the interface is really added/enabled for
batman-adv.

The function to update the hw address information inside the packet_buff
just assumes that the packet_buff is always initialised and thus the
kernel will just oops when we try to change the hw address of a not
already fully enabled interface.

We must always check if the packet_buff is allocated before we try to
change information inside of it.

Reported-by: Tim Glaremin <[email protected]>
Reported-by: Lemonde <[email protected]>
Signed-off-by: Sven Eckelmann <[email protected]>
Cc: stable <[email protected]>
Signed-off-by: Sven Eckelmann <[email protected]>
---
 batman-adv/hard-interface.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/batman-adv/hard-interface.c b/batman-adv/hard-interface.c
index eb26026..9d0a47c 100644
--- a/batman-adv/hard-interface.c
+++ b/batman-adv/hard-interface.c
@@ -138,6 +138,9 @@ static bool hardif_is_iface_up(struct batman_if *batman_if)
 
 static void update_mac_addresses(struct batman_if *batman_if)
 {
+       if (!batman_if || !batman_if->packet_buff)
+               return;
+
        addr_to_string(batman_if->addr_str, batman_if->net_dev->dev_addr);
 
        memcpy(((struct batman_packet *)(batman_if->packet_buff))->orig,
@@ -397,6 +400,7 @@ static struct batman_if *hardif_add_interface(struct 
net_device *net_dev)
        batman_if->net_dev = net_dev;
        batman_if->soft_iface = NULL;
        batman_if->if_status = IF_NOT_IN_USE;
+       batman_if->packet_buff = NULL;
        INIT_LIST_HEAD(&batman_if->list);
 
        check_known_mac_addr(batman_if->net_dev->dev_addr);
-- 
1.7.1

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