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.
This patch fixes this issue by storing the few bytes we are interested in on the stack before modifying the skb.
Signed-off-by: Linus Lüssing linus.luessing@web.de --- send.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/send.c b/send.c index 9c9cab6..b9a1f15 100644 --- a/send.c +++ b/send.c @@ -257,13 +257,15 @@ static int batadv_send_skb_unicast(struct batadv_priv *bat_priv, struct batadv_orig_node *orig_node, unsigned short vid) { - struct ethhdr *ethhdr = (struct ethhdr *)skb->data; + uint8_t dest[ETH_ALEN]; struct batadv_unicast_packet *unicast_packet; int ret = NET_XMIT_DROP;
if (!orig_node) goto out;
+ memcpy(dest, ((struct ethhdr *)skb->data)->h_dest, sizeof(dest)); + switch (packet_type) { case BATADV_UNICAST: if (!batadv_send_skb_prepare_unicast(skb, orig_node)) @@ -289,7 +291,7 @@ static int batadv_send_skb_unicast(struct batadv_priv *bat_priv, * try to reroute it because the ttvn contained in the header is less * than the current one */ - if (batadv_tt_global_client_is_roaming(bat_priv, ethhdr->h_dest, vid)) + if (batadv_tt_global_client_is_roaming(bat_priv, dest, vid)) unicast_packet->ttvn = unicast_packet->ttvn - 1;
if (batadv_send_skb_to_orig(skb, orig_node, NULL) != NET_XMIT_DROP)