[PATCH batadv] batman-adv: retrieve ethhdr after potential skb realloc on RX

pskb_may_pull() in batadv_interface_rx() could reallocate the buffer behind
the skb. Variables which were pointing to the old buffer need to be
reassigned to avoid an use-after-free.

This was done correctly for the VLAN header but missed for the ethernet
header which is later used for the TT and AP isolation handling.

Reported-by: Sashiko <[email protected]>
Fixes: 48628bb9419f ("batman-adv: softif bridge loop avoidance")
Fixes: 7d2f8a773bae ("batman-adv: Check skb size before using encapsulated ETH+VLAN header")
Signed-off-by: Sven Eckelmann <[email protected]>
---
 net/batman-adv/mesh-interface.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/batman-adv/mesh-interface.c b/net/batman-adv/mesh-interface.c
index e5a55d24..907968a1 100644
--- a/net/batman-adv/mesh-interface.c
+++ b/net/batman-adv/mesh-interface.c
@@ -434,6 +434,7 @@ void batadv_interface_rx(struct net_device *mesh_iface,
 		if (!pskb_may_pull(skb, VLAN_ETH_HLEN))
 			goto dropped;
 
+		ethhdr = eth_hdr(skb);
 		vhdr = skb_vlan_eth_hdr(skb);
 
 		/* drop batman-in-batman packets to prevent loops */

---
base-commit: 70dab058ebed0bc0c66dc40113039129b3089780
change-id: 20260628-skb-post-realloc-1eb51d508d33

Best regards,
--  
Sven Eckelmann <[email protected]>