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

netfilter: ipset: fix performance regression in swap operation

The patch "netfilter: ipset: fix race condition between swap/destroy
and kernel side add/del/test", commit 28628fa9 fixes a race condition.
But the synchronize_rcu() added to the swap function unnecessarily slows
it down: it can safely be moved to destroy and use call_rcu() instead.

Eric Dumazet pointed out that simply calling the destroy functions as
rcu callback does not work: sets with timeout use garbage collectors
which need cancelling at destroy which can wait. Therefore the destroy
functions are split into two: cancelling garbage collectors safely at
executing the command received by netlink and moving the remaining
part only into the rcu callback.

kernel.org https://git.kernel.org/stable/c/653bc5e6d9995d7d5f497c665b321875a626161c [No types assigned]

kernel.org https://git.kernel.org/stable/c/970709a67696b100a57b33af1a3d75fc34b747eb [No types assigned]

kernel.org https://git.kernel.org/stable/c/97f7cf1cd80eeed3b7c808b7c12463295c751001 [No types assigned]

kernel.org https://git.kernel.org/stable/c/a24d5f2ac8ef702a58e55ec276aad29b4bd97e05 [No types assigned]

kernel.org https://git.kernel.org/stable/c/b93a6756a01f4fd2f329a39216f9824c56a66397 [No types assigned]

kernel.org https://git.kernel.org/stable/c/c2dc077d8f722a1c73a24e674f925602ee5ece49 [No types assigned]

kernel.org https://git.kernel.org/stable/c/c7f2733e5011bfd136f1ca93497394d43aa76225 [No types assigned]