batman-adv: reject oversized global TT response buffers

batman-adv: fix tpmeter counter underflow during shutdown

batman-adv: dat: handle forward allocation error

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

batman-adv: Avoid double-rtnllock ELP metric worker

batadvvelpgetthroughput() might be called when the RTNL lock is already held. This could be problematic when the work queue item is cancelled via canceldelayedworksync() in batadvvelpifacedisable(). In this case, an rtnllock() would cause a deadlock.

To avoid this, rtnltrylock() was used in this function to skip the retrieval of the ethtool information in case the RTNL lock was already held.

But for cfg80211 interfaces, batadvgetrealnetdev() was called - which also uses rtnllock(). The approach for ethtoolgetlinkksettings() must also be used instead and the lockless version batadvgetrealnetdev() has to be called.