From 0c6599fee6e77795d703c1355cd275b41a32388b Mon Sep 17 00:00:00 2001
From: Konstantin Shandurenko <iam@kostya.sexy>
Date: Thu, 7 Jul 2022 05:18:24 +0300
Subject: [PATCH] Checking that payload length is positive on packets reading
 (#1211)

---
 src/main/java/net/minestom/server/utils/PacketUtils.java | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/main/java/net/minestom/server/utils/PacketUtils.java b/src/main/java/net/minestom/server/utils/PacketUtils.java
index f3e33007d..12f72b697 100644
--- a/src/main/java/net/minestom/server/utils/PacketUtils.java
+++ b/src/main/java/net/minestom/server/utils/PacketUtils.java
@@ -172,6 +172,9 @@ public final class PacketUtils {
                 if (compressed) {
                     final int dataLength = readBuffer.readVarInt();
                     final int payloadLength = packetLength - (readBuffer.readerOffset() - readerStart);
+                    if (payloadLength < 0) {
+                        throw new DataFormatException("Negative payload length " + payloadLength);
+                    }
                     if (dataLength == 0) {
                         // Data is too small to be compressed, payload is following
                         decompressedSize = payloadLength;