@ejona86 @Scottmitch @nmittler @louiscryan is this something we need to fix before 4.1.0.Final ?
 I don't think so. We seem to be conforming to the spec since we're checking the size on the inbound frame.
 @nmittler so closing ?
 @ejona86 thoughts on closing?
 wouldn't hurt to check the write size...make it harder for people to put bad stuff out on the network.
 @Scottmitch care to submit a pr ;) ?
 @normanmaurer - Will do.

@nmittler - Any objections?
 @Scottmitch :heart_eyes:  ;)
 pr pending
 @Scottmitch no objections ... thanks for taking care

http2: writePing does not verify data.readableBytes() == 8
When [writing the ping frame](https://github.com/netty/netty/blob/master/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameWriter.java#L238), we aren't verifying that the length is 8, as required by the spec:

> Receipt of a PING frame with a length field value other than 8 MUST be treated as a connection error (Section 5.4.1) of type FRAME_SIZE_ERROR.

The check [is being performed](https://github.com/netty/netty/blob/master/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameReader.java#L332) for inbound PING frames.

codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameReader.java codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameWriter.java
codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameReader.java codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameWriter.java
diff --git a/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameReader.java b/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameReader.java
index 035fc949e81..4b98985655c 100644
--- a/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameReader.java
+++ b/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameReader.java
@@ -14,9 +14,15 @@
  */
 package io.netty.handler.codec.http2;
 
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufAllocator;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.codec.http2.Http2FrameReader.Configuration;
+
 import static io.netty.handler.codec.http2.Http2CodecUtil.DEFAULT_MAX_FRAME_SIZE;
 import static io.netty.handler.codec.http2.Http2CodecUtil.FRAME_HEADER_LENGTH;
 import static io.netty.handler.codec.http2.Http2CodecUtil.INT_FIELD_LENGTH;
+import static io.netty.handler.codec.http2.Http2CodecUtil.PING_FRAME_PAYLOAD_LENGTH;
 import static io.netty.handler.codec.http2.Http2CodecUtil.PRIORITY_ENTRY_LENGTH;
 import static io.netty.handler.codec.http2.Http2CodecUtil.SETTINGS_INITIAL_WINDOW_SIZE;
 import static io.netty.handler.codec.http2.Http2CodecUtil.SETTINGS_MAX_FRAME_SIZE;
@@ -39,10 +45,6 @@
 import static io.netty.handler.codec.http2.Http2FrameTypes.RST_STREAM;
 import static io.netty.handler.codec.http2.Http2FrameTypes.SETTINGS;
 import static io.netty.handler.codec.http2.Http2FrameTypes.WINDOW_UPDATE;
-import io.netty.buffer.ByteBuf;
-import io.netty.buffer.ByteBufAllocator;
-import io.netty.channel.ChannelHandlerContext;
-import io.netty.handler.codec.http2.Http2FrameReader.Configuration;
 
 /**
  * A {@link Http2FrameReader} that supports all frame types defined by the HTTP/2 specification.
@@ -330,7 +332,7 @@ private void verifyPingFrame() throws Http2Exception {
         if (streamId != 0) {
             throw connectionError(PROTOCOL_ERROR, "A stream ID must be zero.");
         }
-        if (payloadLength != 8) {
+        if (payloadLength != PING_FRAME_PAYLOAD_LENGTH) {
             throw connectionError(FRAME_SIZE_ERROR,
                     "Frame length %d incorrect size for ping.", payloadLength);
         }
diff --git a/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameWriter.java b/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameWriter.java
index 628703b571f..29dbc33c44b 100644
--- a/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameWriter.java
+++ b/codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameWriter.java
@@ -15,6 +15,13 @@
 
 package io.netty.handler.codec.http2;
 
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelFuture;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelPromise;
+import io.netty.handler.codec.http2.Http2CodecUtil.SimpleChannelPromiseAggregator;
+import io.netty.handler.codec.http2.Http2FrameWriter.Configuration;
+
 import static io.netty.buffer.Unpooled.directBuffer;
 import static io.netty.buffer.Unpooled.unmodifiableBuffer;
 import static io.netty.buffer.Unpooled.unreleasableBuffer;
@@ -29,6 +36,7 @@
 import static io.netty.handler.codec.http2.Http2CodecUtil.MAX_UNSIGNED_INT;
 import static io.netty.handler.codec.http2.Http2CodecUtil.MAX_WEIGHT;
 import static io.netty.handler.codec.http2.Http2CodecUtil.MIN_WEIGHT;
+import static io.netty.handler.codec.http2.Http2CodecUtil.PING_FRAME_PAYLOAD_LENGTH;
 import static io.netty.handler.codec.http2.Http2CodecUtil.PRIORITY_ENTRY_LENGTH;
 import static io.netty.handler.codec.http2.Http2CodecUtil.PRIORITY_FRAME_LENGTH;
 import static io.netty.handler.codec.http2.Http2CodecUtil.PUSH_PROMISE_FRAME_HEADER_LENGTH;
@@ -53,13 +61,6 @@
 import static io.netty.handler.codec.http2.Http2FrameTypes.WINDOW_UPDATE;
 import static io.netty.util.internal.ObjectUtil.checkNotNull;
 
-import io.netty.buffer.ByteBuf;
-import io.netty.channel.ChannelFuture;
-import io.netty.channel.ChannelHandlerContext;
-import io.netty.channel.ChannelPromise;
-import io.netty.handler.codec.http2.Http2CodecUtil.SimpleChannelPromiseAggregator;
-import io.netty.handler.codec.http2.Http2FrameWriter.Configuration;
-
 /**
  * A {@link Http2FrameWriter} that supports all frame types defined by the HTTP/2 specification.
  */
@@ -240,6 +241,7 @@ public ChannelFuture writePing(ChannelHandlerContext ctx, boolean ack, ByteBuf d
         SimpleChannelPromiseAggregator promiseAggregator =
                 new SimpleChannelPromiseAggregator(promise, ctx.channel(), ctx.executor());
         try {
+            verifyPingPayload(data);
             Http2Flags flags = ack ? new Http2Flags().ack(true) : new Http2Flags();
             ByteBuf buf = ctx.alloc().buffer(FRAME_HEADER_LENGTH);
             writeFrameHeaderInternal(buf, data.readableBytes(), PING, flags, 0);
@@ -545,4 +547,10 @@ private static void verifyWindowSizeIncrement(int windowSizeIncrement) {
             throw new IllegalArgumentException("WindowSizeIncrement must be >= 0");
         }
     }
+
+    private static void verifyPingPayload(ByteBuf data) {
+        if (data == null || data.readableBytes() != PING_FRAME_PAYLOAD_LENGTH) {
+            throw new IllegalArgumentException("Opaque data must be " + PING_FRAME_PAYLOAD_LENGTH + " bytes");
+        }
+    }
 }
