batman-adv: fix potential kernel paging error for unicast transmissions
batadv_send_skb_prepare_unicast(_4addr) might reallocate the
skb's data. If it does then our ethhdr pointer is not valid
anymore in batadv_send_skb_unicast(), resulting in a kernel
paging error.
Fixing this by refetching the ethhdr pointer after the
potential reallocation.
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
diff --git a/net/batman-adv/send.c b/net/batman-adv/send.c
index 579f5f0..843febd 100644
--- a/net/batman-adv/send.c
+++ b/net/batman-adv/send.c
@@ -254,9 +254,9 @@
struct batadv_orig_node *orig_node,
unsigned short vid)
{
- struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
+ struct ethhdr *ethhdr;
struct batadv_unicast_packet *unicast_packet;
- int ret = NET_XMIT_DROP;
+ int ret = NET_XMIT_DROP, hdr_size;
if (!orig_node)
goto out;
@@ -265,12 +265,16 @@
case BATADV_UNICAST:
if (!batadv_send_skb_prepare_unicast(skb, orig_node))
goto out;
+
+ hdr_size = sizeof(*unicast_packet);
break;
case BATADV_UNICAST_4ADDR:
if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, skb,
orig_node,
packet_subtype))
goto out;
+
+ hdr_size = sizeof(struct batadv_unicast_4addr_packet);
break;
default:
/* this function supports UNICAST and UNICAST_4ADDR only. It
@@ -279,6 +283,7 @@
goto out;
}
+ ethhdr = (struct ethhdr *)(skb->data + hdr_size);
unicast_packet = (struct batadv_unicast_packet *)skb->data;
/* inform the destination node that we are still missing a correct route