Set element addition error path decrements reference counter on chains
twice: once on element release and again via nft_data_release().
Then, d6b478666f ("netfilter: nf_tables: fix underflow in object
reference counter") incorrectly fixed this by removing the stateful
object reference count decrement.
Restore the stateful object decrement as in b91d903688 ("netfilter:
nf_tables: fix leaking object reference count") and let
nft_data_release() decrement the chain reference counter, so this is
done only once.
Fixes: d6b478666f ("netfilter: nf_tables: fix underflow in object reference counter")
Fixes: 628bd3e49c ("netfilter: nf_tables: drop map element references from preparation phase")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
b389139f12