netfilter: nf_tables: avoid BUG_ON usage

[ Upstream commit fa5950e4 ]

None of these spots really needs to crash the kernel.
In one two cases we can jsut report error to userspace, in the other
cases we can just use WARN_ON (and leak memory instead).
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

net/netfilter/nf_tables_api.c

@@ -1031,7 +1031,8 @@ static int nf_tables_deltable(struct net *net, struct sock *nlsk,
 
 static void nf_tables_table_destroy(struct nft_ctx *ctx)
 {
-	BUG_ON(ctx->table->use > 0);
+	if (WARN_ON(ctx->table->use > 0))
+		return;
 
 	rhltable_destroy(&ctx->table->chains_ht);
 	kfree(ctx->table->name);
@@ -1446,7 +1447,8 @@ static void nf_tables_chain_destroy(struct nft_ctx *ctx)
 {
 	struct nft_chain *chain = ctx->chain;
 
-	BUG_ON(chain->use > 0);
+	if (WARN_ON(chain->use > 0))
+		return;
 
 	/* no concurrent access possible anymore */
 	nf_tables_chain_free_chain_rules(chain);
@@ -7253,7 +7255,8 @@ int __nft_release_basechain(struct nft_ctx *ctx)
 {
 	struct nft_rule *rule, *nr;
 
-	BUG_ON(!nft_is_base_chain(ctx->chain));
+	if (WARN_ON(!nft_is_base_chain(ctx->chain)))
+		return 0;
 
 	nf_tables_unregister_hook(ctx->net, ctx->chain->table, ctx->chain);
 	list_for_each_entry_safe(rule, nr, &ctx->chain->rules, list) {

net/netfilter/nft_cmp.c

@@ -79,7 +79,8 @@ static int nft_cmp_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 
 	err = nft_data_init(NULL, &priv->data, sizeof(priv->data), &desc,
 			    tb[NFTA_CMP_DATA]);
-	BUG_ON(err < 0);
+	if (err < 0)
+		return err;
 
 	priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
 	err = nft_validate_register_load(priv->sreg, desc.len);
@@ -129,7 +130,8 @@ static int nft_cmp_fast_init(const struct nft_ctx *ctx,
 
 	err = nft_data_init(NULL, &data, sizeof(data), &desc,
 			    tb[NFTA_CMP_DATA]);
-	BUG_ON(err < 0);
+	if (err < 0)
+		return err;
 
 	priv->sreg = nft_parse_register(tb[NFTA_CMP_SREG]);
 	err = nft_validate_register_load(priv->sreg, desc.len);

net/netfilter/nft_reject.c

@@ -94,7 +94,8 @@ static u8 icmp_code_v4[NFT_REJECT_ICMPX_MAX + 1] = {
 
 int nft_reject_icmp_code(u8 code)
 {
-	BUG_ON(code > NFT_REJECT_ICMPX_MAX);
+	if (WARN_ON_ONCE(code > NFT_REJECT_ICMPX_MAX))
+		return ICMP_NET_UNREACH;
 
 	return icmp_code_v4[code];
 }
@@ -111,7 +112,8 @@ static u8 icmp_code_v6[NFT_REJECT_ICMPX_MAX + 1] = {
 
 int nft_reject_icmpv6_code(u8 code)
 {
-	BUG_ON(code > NFT_REJECT_ICMPX_MAX);
+	if (WARN_ON_ONCE(code > NFT_REJECT_ICMPX_MAX))
+		return ICMPV6_NOROUTE;
 
 	return icmp_code_v6[code];
 }