From: Florian Westphal <fw@strlen.de>
Date: Mon, 14 Jul 2025 11:48:24 +0000 (+0200)
Subject: json: BASECHAIN flag no longer implies presence of priority expression
X-Git-Tag: v1.1.4~10
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=715010c61ba25627b57d95d096138013e7c0e194;p=thirdparty%2Fnftables.git

json: BASECHAIN flag no longer implies presence of priority expression

This is a followup to
44ea19364637 ("src: BASECHAIN flag no longer implies presence of priority expression"):
feeding the same bogon file into nft -j we get a very similar crash.

Signed-off-by: Florian Westphal <fw@strlen.de>
---

diff --git a/src/json.c b/src/json.c
index 5d34b27e..977f5566 100644
--- a/src/json.c
+++ b/src/json.c
@@ -294,8 +294,7 @@ static json_t *rule_print_json(struct output_ctx *octx,
 
 static json_t *chain_print_json(const struct chain *chain)
 {
-	json_t *root, *tmp, *devs = NULL;
-	int priority, policy, i;
+	json_t *root;
 
 	root = nft_json_pack("{s:s, s:s, s:s, s:I}",
 			 "family", family2str(chain->handle.family),
@@ -307,8 +306,12 @@ static json_t *chain_print_json(const struct chain *chain)
 		json_object_set_new(root, "comment", json_string(chain->comment));
 
 	if (chain->flags & CHAIN_F_BASECHAIN) {
-		mpz_export_data(&priority, chain->priority.expr->value,
-				BYTEORDER_HOST_ENDIAN, sizeof(int));
+		json_t *tmp = NULL, *devs = NULL;
+		int priority = 0, policy, i;
+
+		if (chain->priority.expr)
+			mpz_export_data(&priority, chain->priority.expr->value,
+					BYTEORDER_HOST_ENDIAN, sizeof(int));
 
 		if (chain->policy) {
 			mpz_export_data(&policy, chain->policy->value,
@@ -317,12 +320,15 @@ static json_t *chain_print_json(const struct chain *chain)
 			policy = NF_ACCEPT;
 		}
 
-		tmp = nft_json_pack("{s:s, s:s, s:i, s:s}",
-				"type", chain->type.str,
-				"hook", hooknum2str(chain->handle.family,
-						    chain->hook.num),
-				"prio", priority,
-				"policy", chain_policy2str(policy));
+		if (chain->type.str)
+			tmp = nft_json_pack("{s:s, s:s, s:i, s:s}",
+					"type", chain->type.str,
+					"hook", hooknum2str(chain->handle.family,
+							    chain->hook.num),
+					"prio", priority,
+					"policy", chain_policy2str(policy));
+		else
+			tmp = NULL;
 
 		for (i = 0; i < chain->dev_array_len; i++) {
 			const char *dev = chain->dev_array[i];
@@ -336,8 +342,10 @@ static json_t *chain_print_json(const struct chain *chain)
 		if (devs)
 			json_object_set_new(root, "dev", devs);
 
-		json_object_update(root, tmp);
-		json_decref(tmp);
+		if (tmp) {
+			json_object_update(root, tmp);
+			json_decref(tmp);
+		}
 	}
 
 	return nft_json_pack("{s:o}", "chain", root);
diff --git a/tests/shell/testcases/bogons/nft-j-f/null_ingress_type_crash b/tests/shell/testcases/bogons/nft-j-f/null_ingress_type_crash
new file mode 100644
index 00000000..2ed88af2
--- /dev/null
+++ b/tests/shell/testcases/bogons/nft-j-f/null_ingress_type_crash
@@ -0,0 +1,6 @@
+table netdev filter1 {
+	chain c {
+		devices = { lo }
+	}
+}
+list ruleset