The mapping parsing logic needs protection agains stack overflows #52098
Description
There has been a report of a node shutting down because of the following StackOverflowError when parsing mappings:
fatal error in thread [elasticsearch[xxxxxxxxxxxxxxxx][masterService#updateTask][T#1]], exiting java.lang.StackOverflowError: null at java.util.Collections$UnmodifiableMap.get(Collections.java:1454) ~[?:1.8.0_121] at org.elasticsearch.index.mapper.Mapper$TypeParser$ParserContext.typeParser(Mapper.java:124) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseProperties(ObjectMapper.java:274) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseObjectOrDocumentTypeProperties(ObjectMapper.java:200) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parse(ObjectMapper.java:173) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseProperties(ObjectMapper.java:280) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseObjectOrDocumentTypeProperties(ObjectMapper.java:200) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parse(ObjectMapper.java:173) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseProperties(ObjectMapper.java:280) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseObjectOrDocumentTypeProperties(ObjectMapper.java:200) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parse(ObjectMapper.java:173) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseProperties(ObjectMapper.java:280) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseObjectOrDocumentTypeProperties(ObjectMapper.java:200) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parse(ObjectMapper.java:173) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseProperties(ObjectMapper.java:280) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseObjectOrDocumentTypeProperties(ObjectMapper.java:200) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parse(ObjectMapper.java:173) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseProperties(ObjectMapper.java:280) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseObjectOrDocumentTypeProperties(ObjectMapper.java:200) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parse(ObjectMapper.java:173) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseProperties(ObjectMapper.java:280) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseObjectOrDocumentTypeProperties(ObjectMapper.java:200) ~[elasticsearch-6.8.6.jar:6.8.6] at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parse(ObjectMapper.java:173) ~[elasticsearch-6.8.6.jar:6.8.6] While this specific mapping was corrupt, Elasticsearch should also have better protection against stack overflow errors.