AZL-83810

In the Linux kernel, the following vulnerability has been resolved:

batman-adv: hold claim backbone gateways by reference

batadvblaaddclaim() can replace claim->backbonegw and drop the old gateway's last reference while readers still follow the pointer.

The netlink claim dump path dereferences claim->backbonegw->orig and takes claim->backbonegw->crclock without pinning the underlying backbone gateway. batadvblacheckclaim() still has the same naked pointer access pattern.

Reuse batadvblaclaimgetbackbone_gw() in both readers so they operate on a stable gateway reference until the read-side work is complete. This keeps the dump and claim-check paths aligned with the lifetime rules introduced for the other BLA claim readers.