tests: net: lwm2m: content_json: Check for overflows

Add checks for int64_t overflows when parsing.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

tests/net/lib/lwm2m/content_json/src/main.c

@@ -525,6 +525,10 @@ ZTEST(net_content_json, test_get_s64)
 		TEST_PAYLOAD(TEST_RES_S64, "v", "9223372036854775807"),
 		TEST_PAYLOAD(TEST_RES_S64, "v", "-9223372036854775808"),
 	};
+	char * const payload_overflow[] = {
+		TEST_PAYLOAD(TEST_RES_S64, "v", "9223372036854775808"),
+		TEST_PAYLOAD(TEST_RES_S64, "v", "-9223372036854775809"),
+	};
 	int64_t expected_value[] = { 0, INT64_MAX, INT64_MIN };
 
 	test_msg.path.res_id = TEST_RES_S64;
@@ -536,6 +540,13 @@ ZTEST(net_content_json, test_get_s64)
 		zassert_true(ret >= 0, "Error reported");
 		zassert_equal(test_s64, expected_value[i], "Invalid value parsed");
 	}
+
+	for (i = 0; i < ARRAY_SIZE(payload_overflow); i++) {
+		test_payload_set(payload_overflow[i]);
+
+		ret = do_write_op_json(&test_msg);
+		zassert_equal(ret, -EINVAL, "Error expected on too large value");
+	}
 }
 
 ZTEST(net_content_json_nodata, test_get_s64_nodata)