前言

呵呵大概是由于最近的这个 “Apache Log4j被曝存在严重高危险级别远程代码执行漏洞”

昨天晚上编译了一下 logging-log4j2-log4j-2.15.0-rc2, 项目需要一个 toolchain.xml 的一个配置, 里面需要配置为 jdk9

因此我的项目配置的 jdk 为 jdk9

然后 idea 里面默认的字节码级别为 jdk8

因此就造成了这个基于 jdk9 编译的 jdk8 的字节码

进而造成了这里的问题

测试用例

首先基于 logging-log4j2-log4j-2.15.0-rc2 项目打包, 基于 jdk9 编译 jdk8 版本的字节码

然后项目中导入 log4j-core 的依赖, 并执行

/**
 * Test01Log4j2Dot15
 *
 * @author Jerry.X.He <970655147@qq.com>
 * @version 1.0
 * @date 2021-12-10 21:11
 */
public class Test01Log4j2Dot15 implements Cloneable {

    // logger
    private static Logger logger = LogManager.getLogger();

    private int x1;
    private int x2;
    private int x3;
    private int x4;
    private int x5;
    private int x6;

    // Test01Log4j2Dot15
    public static void main(String[] args) throws Exception {

        logger.error("xxx");

        ByteBuffer buf = ByteBuffer.allocateDirect(12);
        System.gc();
        buf.clear();

    }

}

报错如下

Exception in thread "main" java.lang.NoSuchMethodError: java.nio.ByteBuffer.clear()Ljava/nio/ByteBuffer;
	at org.apache.logging.log4j.core.appender.OutputStreamManager.flushBuffer(OutputStreamManager.java:286)
	at org.apache.logging.log4j.core.appender.OutputStreamManager.flush(OutputStreamManager.java:294)
	at org.apache.logging.log4j.core.appender.OutputStreamManager.closeOutputStream(OutputStreamManager.java:299)
	at org.apache.logging.log4j.core.appender.OutputStreamManager.releaseSub(OutputStreamManager.java:122)
	at org.apache.logging.log4j.core.appender.AbstractManager.stop(AbstractManager.java:86)
	at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.stop(AbstractOutputStreamAppender.java:162)
	at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.stop(AbstractOutputStreamAppender.java:156)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.stop(AbstractConfiguration.java:399)
	at org.apache.logging.log4j.core.AbstractLifeCycle.stop(AbstractLifeCycle.java:136)
	at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:631)
	at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:699)
	at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:716)
	at org.apache.logging.log4j.core.LoggerContext.start(LoggerContext.java:270)
	at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:155)
	at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:47)
	at org.apache.logging.log4j.LogManager.getContext(LogManager.java:196)
	at org.apache.logging.log4j.LogManager.getLogger(LogManager.java:599)
	at org.apache.logging.log4j.LogManager.getLogger(LogManager.java:585)
	at com.hx.test.Test01Log4j2Dot15.<clinit>(Test01Log4j2Dot15.java:19)

class 版本为 52, 对应于 jdk8

报错的方法调用的地方, clear 方法, 注意 signature 为 ()Ljava/nio/ByteBuffer;

在 jdk8 中 Buffer.clear 方法如下, 是 final 的, 并且返回值为 Buffer

在 jdk9 中 Buffer.clear 修改为了非final, 并且 ByteBuffer 重写了 clear 方法, 返回类型更新为了 ByteBuffer

基于 HotSpotVM 的调试

拿到这个 "基于 jdk9 编译的 jdk8版本的字节码", 拿到 jdk8 中去执行, 报错便是上面提到的日志

Exception in thread "main" java.lang.NoSuchMethodError: java.nio.ByteBuffer.clear()Ljava/nio/ByteBuffer;
	at org.apache.logging.log4j.core.appender.OutputStreamManager.flushBuffer(OutputStreamManager.java:286)
	at org.apache.logging.log4j.core.appender.OutputStreamManager.flush(OutputStreamManager.java:294)
	at org.apache.logging.log4j.core.appender.OutputStreamManager.closeOutputStream(OutputStreamManager.java:299)
	at org.apache.logging.log4j.core.appender.OutputStreamManager.releaseSub(OutputStreamManager.java:122)
	at org.apache.logging.log4j.core.appender.AbstractManager.stop(AbstractManager.java:86)
	at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.stop(AbstractOutputStreamAppender.java:162)
	at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.stop(AbstractOutputStreamAppender.java:156)
	at org.apache.logging.log4j.core.config.AbstractConfiguration.stop(AbstractConfiguration.java:399)
	at org.apache.logging.log4j.core.AbstractLifeCycle.stop(AbstractLifeCycle.java:136)
	at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:631)
	at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:699)
	at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:716)
	at org.apache.logging.log4j.core.LoggerContext.start(LoggerContext.java:270)
	at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:155)
	at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:47)
	at org.apache.logging.log4j.LogManager.getContext(LogManager.java:196)
	at org.apache.logging.log4j.LogManager.getLogger(LogManager.java:599)
	at org.apache.logging.log4j.LogManager.getLogger(LogManager.java:585)
	at com.hx.test.Test01Log4j2Dot15.<clinit>(Test01Log4j2Dot15.java:19)

大致的原因如下, 在 ByteBuffer 以及其基类中 lookup 方法 ByteBuffer clear(), 结果没有找到

然后抛出了 NoSuchMethodError