Streaming: Prevent AIOOBE when verifying large signed packets

(prep for PQ)

apps/streaming/java/src/net/i2p/client/streaming/impl/Packet.java

@@ -792,7 +792,7 @@ class Packet {
         
         int size = writtenSize();
         
-        if (buffer == null)
+        if (buffer == null || size > buffer.length)
             buffer = new byte[size];
         if (isFlagSet(FLAG_SIGNATURE_OFFLINE)) {
             if (_transientExpires < ctx.clock().now()) {