netfilter: nft_set_pipapo: release elements in clone from abort path

New elements that reside in the clone are not released in case that the
transaction is aborted.

[16302.231754] ------------[ cut here ]------------
[16302.231756] WARNING: CPU: 0 PID: 100509 at net/netfilter/nf_tables_api.c:1864 nf_tables_chain_destroy+0x26/0x127 [nf_tables]
[...]
[16302.231882] CPU: 0 PID: 100509 Comm: nft Tainted: G W 5.19.0-rc3+ #155
[...]
[16302.231887] RIP: 0010:nf_tables_chain_destroy+0x26/0x127 [nf_tables]
[16302.231899] Code: f3 fe ff ff 41 55 41 54 55 53 48 8b 6f 10 48 89 fb 48 c7 c7 82 96 d9 a0 8b 55 50 48 8b 75 58 e8 de f5 92 e0 83 7d 50 00 74 09 <0f> 0b 5b 5d 41 5c 41 5d c3 4c 8b 65 00 48 8b 7d 08 49 39 fc 74 05
[...]
[16302.231917] Call Trace:
[16302.231919] <TASK>
[16302.231921] __nf_tables_abort.cold+0x23/0x28 [nf_tables]
[16302.231934] nf_tables_abort+0x30/0x50 [nf_tables]
[16302.231946] nfnetlink_rcv_batch+0x41a/0x840 [nfnetlink]
[16302.231952] ? __nla_validate_parse+0x48/0x190
[16302.231959] nfnetlink_rcv+0x110/0x129 [nfnetlink]
[16302.231963] netlink_unicast+0x211/0x340
[16302.231969] netlink_sendmsg+0x21e/0x460

Add nft_set_pipapo_match_destroy() helper function to release the
elements in the lookup tables.

Stefano Brivio says: "We additionally look for elements pointers in the
cloned matching data if priv->dirty is set, because that means that
cloned data might point to additional elements we did not commit to the
working copy yet (such as the abort path case, but perhaps not limited
to it)."

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Reviewed-by: Stefano Brivio <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

net/netfilter/nft_set_pipapo.c

···
 }
 
 /**
+ * nft_set_pipapo_match_destroy() - Destroy elements from key mapping array
+ * @set:	nftables API set representation
+ * @m:		matching data pointing to key mapping array
+ */
+static void nft_set_pipapo_match_destroy(const struct nft_set *set,
+					 struct nft_pipapo_match *m)
+{
+	struct nft_pipapo_field *f;
+	int i, r;
+
+	for (i = 0, f = m->f; i < m->field_count - 1; i++, f++)
+		;
+
+	for (r = 0; r < f->rules; r++) {
+		struct nft_pipapo_elem *e;
+
+		if (r < f->rules - 1 && f->mt[r + 1].e == f->mt[r].e)
+			continue;
+
+		e = f->mt[r].e;
+
+		nft_set_elem_destroy(set, e, true);
+	}
+}
+
+/**
  * nft_pipapo_destroy() - Free private data for set and all committed elements
  * @set:	nftables API set representation
  */
···
 {
 	struct nft_pipapo *priv = nft_set_priv(set);
 	struct nft_pipapo_match *m;
-	struct nft_pipapo_field *f;
-	int i, r, cpu;
+	int cpu;
 
 	m = rcu_dereference_protected(priv->match, true);
 	if (m) {
 		rcu_barrier();
 
-		for (i = 0, f = m->f; i < m->field_count - 1; i++, f++)
-			;
-
-		for (r = 0; r < f->rules; r++) {
-			struct nft_pipapo_elem *e;
-
-			if (r < f->rules - 1 && f->mt[r + 1].e == f->mt[r].e)
-				continue;
-
-			e = f->mt[r].e;
-
-			nft_set_elem_destroy(set, e, true);
-		}
+		nft_set_pipapo_match_destroy(set, m);
 
 #ifdef NFT_PIPAPO_ALIGN
 		free_percpu(m->scratch_aligned);
···
 	}
 
 	if (priv->clone) {
+		m = priv->clone;
+
+		if (priv->dirty)
+			nft_set_pipapo_match_destroy(set, m);
+
 #ifdef NFT_PIPAPO_ALIGN
 		free_percpu(priv->clone->scratch_aligned);
 #endif