part.getString will cause OOM without checking maxPostSize, checking maxPostSize first will avoid OOM caused by huge string

[tianshuang]

In our online server, when the client sends a huge string (hundreds of megabytes) to the server via multipart/form-data, OOM occurs, and the maxPostSize check logic is not executed

[markt-asf]

This report, and the proposed solution is invalid. maxPostSize does not, and should not, apply to a multi-part request explicitly parsed via Request.getParts() or Request.getPart(String).
Further advice is available from the Tomcat users mailing list: http://tomcat.apache.org/lists.html

[tianshuang]

I adjusted to check the maxPostSize first to avoid the OOM problem, part.getString will trigger OOM when the string is huge.

[tianshuang]

If part.getString is called before checking maxPostSize, it may trigger OOM.

[tianshuang]

stack trace:

  at java.lang.OutOfMemoryError.<init>()V (OutOfMemoryError.java:48)
  at java.lang.StringCoding$StringDecoder.decode([BII)[C (StringCoding.java:149)
  at java.lang.StringCoding.decode(Ljava/lang/String;[BII)[C (StringCoding.java:193)
  at java.lang.String.<init>([BIILjava/lang/String;)V (String.java:426)
  at java.lang.String.<init>([BLjava/lang/String;)V (String.java:491)
  at org.apache.tomcat.util.http.fileupload.disk.DiskFileItem.getString(Ljava/lang/String;)Ljava/lang/String; (DiskFileItem.java:327)
  at org.apache.catalina.core.ApplicationPart.getString(Ljava/lang/String;)Ljava/lang/String; (ApplicationPart.java:127)
  at org.apache.catalina.connector.Request.parseParts(Z)V (Request.java:2919)
  at org.apache.catalina.connector.Request.getParts()Ljava/util/Collection; (Request.java:2810)
  at org.apache.catalina.connector.RequestFacade.getParts()Ljava/util/Collection; (RequestFacade.java:1084)
  at org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.parseRequest(Ljavax/servlet/http/HttpServletRequest;)V (StandardMultipartHttpServletRequest.java:93)
  at org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.<init>(Ljavax/servlet/http/HttpServletRequest;Z)V (StandardMultipartHttpServletRequest.java:86)
  at org.springframework.web.multipart.support.StandardServletMultipartResolver.resolveMultipart(Ljavax/servlet/http/HttpServletRequest;)Lorg/springframework/web/multipart/MultipartHttpServletRequest; (StandardServletMultipartResolver.java:91)
  at org.springframework.web.servlet.DispatcherServlet.checkMultipart(Ljavax/servlet/http/HttpServletRequest;)Ljavax/servlet/http/HttpServletRequest; (DispatcherServlet.java:1128)
  at org.springframework.web.servlet.DispatcherServlet.doDispatch(Ljavax/servlet/http/HttpServletRequest;Ljavax/servlet/http/HttpServletResponse;)V (DispatcherServlet.java:960)
  at org.springframework.web.servlet.DispatcherServlet.doService(Ljavax/servlet/http/HttpServletRequest;Ljavax/servlet/http/HttpServletResponse;)V (DispatcherServlet.java:925)
  at org.springframework.web.servlet.FrameworkServlet.processRequest(Ljavax/servlet/http/HttpServletRequest;Ljavax/servlet/http/HttpServletResponse;)V (FrameworkServlet.java:974)
  at org.springframework.web.servlet.FrameworkServlet.doPost(Ljavax/servlet/http/HttpServletRequest;Ljavax/servlet/http/HttpServletResponse;)V (FrameworkServlet.java:877)
  at javax.servlet.http.HttpServlet.service(Ljavax/servlet/http/HttpServletRequest;Ljavax/servlet/http/HttpServletResponse;)V (HttpServlet.java:652)
  at org.springframework.web.servlet.FrameworkServlet.service(Ljavax/servlet/http/HttpServletRequest;Ljavax/servlet/http/HttpServletResponse;)V (FrameworkServlet.java:851)
  at javax.servlet.http.HttpServlet.service(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;)V (HttpServlet.java:733)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;)V (ApplicationFilterChain.java:231)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;)V (ApplicationFilterChain.java:166)
  at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(Ljavax/servlet/http/HttpServletRequest;Ljavax/servlet/http/HttpServletResponse;Ljavax/servlet/FilterChain;)V (HttpPutFormContentFilter.java:109)
  at org.springframework.web.filter.OncePerRequestFilter.doFilter(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;Ljavax/servlet/FilterChain;)V (OncePerRequestFilter.java:107)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;)V (ApplicationFilterChain.java:193)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;)V (ApplicationFilterChain.java:166)
  at org.apache.tomcat.websocket.server.WsFilter.doFilter(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;Ljavax/servlet/FilterChain;)V (WsFilter.java:52)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;)V (ApplicationFilterChain.java:193)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;)V (ApplicationFilterChain.java:166)
  at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(Ljavax/servlet/http/HttpServletRequest;Ljavax/servlet/http/HttpServletResponse;Ljavax/servlet/FilterChain;)V (CharacterEncodingFilter.java:200)
  at org.springframework.web.filter.OncePerRequestFilter.doFilter(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;Ljavax/servlet/FilterChain;)V (OncePerRequestFilter.java:107)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;)V (ApplicationFilterChain.java:193)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;)V (ApplicationFilterChain.java:166)
  at org.apache.catalina.core.StandardWrapperValve.invoke(Lorg/apache/catalina/connector/Request;Lorg/apache/catalina/connector/Response;)V (StandardWrapperValve.java:199)
  at org.apache.catalina.core.StandardContextValve.invoke(Lorg/apache/catalina/connector/Request;Lorg/apache/catalina/connector/Response;)V (StandardContextValve.java:97)
  at org.apache.catalina.authenticator.AuthenticatorBase.invoke(Lorg/apache/catalina/connector/Request;Lorg/apache/catalina/connector/Response;)V (AuthenticatorBase.java:544)
  at org.apache.catalina.core.StandardHostValve.invoke(Lorg/apache/catalina/connector/Request;Lorg/apache/catalina/connector/Response;)V (StandardHostValve.java:143)
  at org.apache.catalina.valves.ErrorReportValve.invoke(Lorg/apache/catalina/connector/Request;Lorg/apache/catalina/connector/Response;)V (ErrorReportValve.java:81)
  at org.apache.catalina.core.StandardEngineValve.invoke(Lorg/apache/catalina/connector/Request;Lorg/apache/catalina/connector/Response;)V (StandardEngineValve.java:78)
  at org.apache.catalina.connector.CoyoteAdapter.service(Lorg/apache/coyote/Request;Lorg/apache/coyote/Response;)V (CoyoteAdapter.java:343)
  at org.apache.coyote.http11.Http11Processor.service(Lorg/apache/tomcat/util/net/SocketWrapperBase;)Lorg/apache/tomcat/util/net/AbstractEndpoint$Handler$SocketState; (Http11Processor.java:616)
  at org.apache.coyote.AbstractProcessorLight.process(Lorg/apache/tomcat/util/net/SocketWrapperBase;Lorg/apache/tomcat/util/net/SocketEvent;)Lorg/apache/tomcat/util/net/AbstractEndpoint$Handler$SocketState; (AbstractProcessorLight.java:65)
  at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(Lorg/apache/tomcat/util/net/SocketWrapperBase;Lorg/apache/tomcat/util/net/SocketEvent;)Lorg/apache/tomcat/util/net/AbstractEndpoint$Handler$SocketState; (AbstractProtocol.java:818)
  at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun()V (NioEndpoint.java:1626)
  at org.apache.tomcat.util.net.SocketProcessorBase.run()V (SocketProcessorBase.java:49)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(Ljava/util/concurrent/ThreadPoolExecutor$Worker;)V (ThreadPoolExecutor.java:1149)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run()V (ThreadPoolExecutor.java:624)
  at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run()V (TaskThread.java:61)
  at java.lang.Thread.run()V (Thread.java:748)

[tianshuang]

My solution did not change the original semantics. Please take a closer look. It just adjusted the calling order of part.getString to avoid the OOM problem of large strings. After I compiled tomcat locally and tested it, I solved the OOM problem when part.getString was called in advance for huge strings and insufficient memory.

[markt-asf]

Re-opening to take another look.