netfilter: nf_tables: release flow rule object from commit path

netfilter: nf_tables: release flow rule object from commit path

[ Upstream commit 26b5934ff4194e13196bedcba373cd4915071d0e ]

No need to postpone this to the commit release path, since no packets
are walking over this object, this is accessed from control plane only.
This helped uncovered UAF triggered by races with the netlink notifier.

Fixes: 9dd732e0bdf5 ("netfilter: nf_tables: memleak flow rule from commit path")
Reported-by: syzbot+8f747f62763bc6c32916@syzkaller.appspotmail.com
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>