UPSTREAM: netfilter: nft_set_pipapo: skip inactive elements during set walk

commit 317eb968 upstream.

Otherwise set elements can be deactivated twice which will cause a crash.

Bug: 316310313
Reported-by: Xingyuan Mo <hdthky0@gmail.com>
Fixes: 3c4287f6 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 189c2a82)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I27fb6ee806642e23ca02700763a387341dd463e6