netty: CorruptedFrameException in LengthFieldBasedFrameDecoder when using Epoll with AdaptiveRecvByteBufAllocator

Been using this code for years:

    new LengthFieldBasedFrameDecoder(1400, 0, 2, -2, 0, true),

It worked with NIO for a long time, and with EPOLL for several Netty versions. But now it fails with the exception seen below.

Expected behavior

Frames are read correctly.

Actual behavior

Exception is thrown when using EPOLL mode:

    io.netty.handler.codec.CorruptedFrameException: Adjusted frame length (0) is less than lengthFieldEndOffset: 2
    	at io.netty.handler.codec.LengthFieldBasedFrameDecoder.failOnFrameLengthLessThanLengthFieldEndOffset(LengthFieldBasedFrameDecoder.java:360)
    	at io.netty.handler.codec.LengthFieldBasedFrameDecoder.decode(LengthFieldBasedFrameDecoder.java:417)
    	at io.netty.handler.codec.LengthFieldBasedFrameDecoder.decode(LengthFieldBasedFrameDecoder.java:334)
    	at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:503)
    	at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:442)
    	at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:281)
    	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:374)
    	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:360)
    	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:352)
    	at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:102)
    	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:374)
    	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:360)
    	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:352)
    	at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:287)
    	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:374)
    	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:360)
    	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:352)
    	at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1422)
    	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:374)
    	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:360)
    	at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:931)
    	at io.netty.channel.epoll.EpollDatagramChannel.read(EpollDatagramChannel.java:688)
    	at io.netty.channel.epoll.EpollDatagramChannel.access$100(EpollDatagramChannel.java:57)
    	at io.netty.channel.epoll.EpollDatagramChannel$EpollDatagramChannelUnsafe.epollInReady(EpollDatagramChannel.java:507)
    	at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe$1.run(AbstractEpollChannel.java:394)
    	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
    	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:510)
    	at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:413)
    	at io.netty.util.concurrent.SingleThreadEventExecutor$6.run(SingleThreadEventExecutor.java:1050)
    	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
    	at java.base/java.lang.Thread.run(Thread.java:834)

Steps to reproduce

Unable to provide access to private data stream.

Netty version

4.1.43.Final

JVM version (e.g. java -version)

openjdk version “11.0.5” 2019-10-15 OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.5+10) OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.5+10, mixed mode)

OS version (e.g. uname -a)

Linux 4.15.0-70-generic #79-Ubuntu SMP Tue Nov 12 10:36:11 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux