netfilter: nf_tables: deactivate catchall elements in next generation

cve CVE-2023-4569
commit-author Florian Westphal <fw@strlen.de>
commit 90e5b34

When flushing, individual set elements are disabled in the next
generation via the ->flush callback.

Catchall elements are not disabled.  This is incorrect and may lead to
double-deactivations of catchall elements which then results in memory
leaks:

WARNING: CPU: 1 PID: 3300 at include/net/netfilter/nf_tables.h:1172 nft_map_deactivate+0x549/0x730
CPU: 1 PID: 3300 Comm: nft Not tainted 6.5.0-rc5+ #60
RIP: 0010:nft_map_deactivate+0x549/0x730
 [..]
 ? nft_map_deactivate+0x549/0x730
 nf_tables_delset+0xb66/0xeb0

(the warn is due to nft_use_dec() detecting underflow).

Fixes: aaa3104 ("netfilter: nftables: add catch-all set element support")
	Reported-by: lonial con <kongln9170@gmail.com>
	Signed-off-by: Florian Westphal <fw@strlen.de>
(cherry picked from commit 90e5b34)
	Signed-off-by: Marcin Wcisło <marcin.wcislo@conclusive.pl>

Author: pvts-mat

net/netfilter/nf_tables_api.c

@@ -6856,6 +6856,7 @@ static int nft_set_catchall_flush(const struct nft_ctx *ctx,
 		ret = __nft_set_catchall_flush(ctx, set, &elem);
 		if (ret < 0)
 			break;
+		nft_set_elem_change_active(ctx->net, set, ext);
 	}
 
 	return ret;