netfilter: nft_set_pipapo: stop GC iteration if GC transaction allocation fails

jira VULN-430
cve CVE-2023-4244
commit-author Pablo Neira Ayuso <pablo@netfilter.org>
commit 6d365ea

nft_trans_gc_queue_sync() enqueues the GC transaction and it allocates a
new one. If this allocation fails, then stop this GC sync run and retry
later.

Fixes: 5f68718 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
	Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
(cherry picked from commit 6d365ea)
	Signed-off-by: Marcin Wcisło <marcin.wcislo@conclusive.pl>

Author: pvts-mat

net/netfilter/nft_set_pipapo.c

@@ -1597,7 +1597,7 @@ static void pipapo_gc(const struct nft_set *_set, struct nft_pipapo_match *m)
 
 			gc = nft_trans_gc_queue_sync(gc, GFP_ATOMIC);
 			if (!gc)
-				break;
+				return;
 
 			nft_pipapo_gc_deactivate(net, set, e);
 			pipapo_drop(m, rulemap);