netfilter: nf_tables: GC transaction race with netns dismantle

JIRA: https://issues.redhat.com/browse/RHEL-1720
JIRA: https://issues.redhat.com/browse/RHEL-1721
Upstream Status: commit 02c6c24

commit 02c6c24
Author: Pablo Neira Ayuso <[email protected]>
Date:   Tue Aug 15 15:39:01 2023 +0200

    netfilter: nf_tables: GC transaction race with netns dismantle

    Use maybe_get_net() since GC workqueue might race with netns exit path.

    Fixes: 5f68718 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
    Signed-off-by: Pablo Neira Ayuso <[email protected]>
    Signed-off-by: Florian Westphal <[email protected]>

Signed-off-by: Florian Westphal <[email protected]>

Author: fw-strlen

net/netfilter/nf_tables_api.c

@@ -9145,9 +9145,14 @@ struct nft_trans_gc *nft_trans_gc_alloc(struct nft_set *set,
 	if (!trans)
 		return NULL;
 
+	trans->net = maybe_get_net(net);
+	if (!trans->net) {
+		kfree(trans);
+		return NULL;
+	}
+
 	refcount_inc(&set->refs);
 	trans->set = set;
-	trans->net = get_net(net);
 	trans->seq = gc_seq;
 
 	return trans;