diff --git a/gnumach/ipc/ipc_mqueue.c b/gnumach/ipc/ipc_mqueue.c
index f770afb..834eb16 100644
--- a/gnumach/ipc/ipc_mqueue.c
+++ b/gnumach/ipc/ipc_mqueue.c
@@ -3,7 +3,6 @@
  * Copyright (c) 1991,1990,1989 Carnegie Mellon University.
  * Copyright (c) 1993,1994 The University of Utah and
  * the Computer Systems Laboratory (CSL).
- * Copyright (c) 2026 Alperen ERKAN - Stux6 Technology
  * All rights reserved.
  *
  * Permission to use, copy, modify and distribute this software and its
@@ -28,11 +27,11 @@
  * the rights to redistribute these changes.
  */
 /*
- *	File:	ipc/ipc_mqueue.c
- *	Author:	Rich Draves
- *	Date:	2026 
+ *  File:   ipc/ipc_mqueue.c
+ *  Author: Rich Draves / Alperen ERKAN 
+ *  Date:   2026 
  *
- *	Functions to manipulate IPC message queues.
+ *  Functions to manipulate IPC message queues.
  */
 
 #include <mach/port.h>
@@ -52,6 +51,10 @@
 #include <ipc/ipc_space.h>
 #include <ipc/ipc_marequest.h>
 
+/* 
+ * An absolute message queue upper limit to prevent OOM and memory exhaustion.
+ */
+#define IPC_MQUEUE_HARD_LIMIT 65536
 
 
 /*
@@ -156,6 +159,8 @@ ipc_mqueue_changed(
 
 /*
  *	Routine:	ipc_mqueue_send
+ *  Author :    Alperen ERKAN 
+ * 						 2026
  *	Purpose:
  *		Send a message to a port.  The message holds a reference
  *		for the destination port in the msgh_remote_port field.
@@ -180,8 +185,16 @@ ipc_mqueue_send(
 {
 	ipc_port_t port;
 
+	/* Defensive C: Checking the incoming message object and destination port */
+	if (kmsg == IKM_NULL) {
+    	return MACH_SEND_INVALID_DATA;
+	}
+
 	port = (ipc_port_t) kmsg->ikm_header.msgh_remote_port;
-	assert(IP_VALID(port));
+
+	if (!IP_VALID(port)) {
+   	   return MACH_SEND_INVALID_DEST;
+	}
 
 	ip_lock(port);
 
@@ -230,17 +243,17 @@ ipc_mqueue_send(
 		}
 
 		/*
-		 *  Don't block if:
-		 *	1) We're under the queue limit.
-		 *	2) Caller used the MACH_SEND_ALWAYS internal option.
-		 *	3) Message is sent to a send-once right.
-		 */
-
-		if ((port->ip_msgcount < port->ip_qlimit) ||
-		    (option & MACH_SEND_ALWAYS) ||
-		    (MACH_MSGH_BITS_REMOTE(kmsg->ikm_header.msgh_bits) ==
-						MACH_MSG_TYPE_PORT_SEND_ONCE))
-			break;
+         *  Don't block if:
+         *  1) We're under the queue limit.
+         *  2) Caller used MACH_SEND_ALWAYS but we are under the hard safety limit.
+         *  3) Message is sent to a send-once right.
+         */
+
+        if ((port->ip_msgcount < port->ip_qlimit) ||
+            ((option & MACH_SEND_ALWAYS) && (port->ip_msgcount < IPC_MQUEUE_HARD_LIMIT)) ||
+            (MACH_MSGH_BITS_REMOTE(kmsg->ikm_header.msgh_bits) ==
+                        MACH_MSG_TYPE_PORT_SEND_ONCE))
+            break;
 
 		/* must block waiting for queue to clear */
 
@@ -263,45 +276,49 @@ ipc_mqueue_send(
 		counter(c_ipc_mqueue_send_block++);
 		thread_block(thread_no_continuation);
 		ip_lock(port);
-
+  
 		/* why did we wake up? */
 
-		if (self->ith_state == MACH_MSG_SUCCESS)
-			continue;
-		assert(self->ith_state == MACH_SEND_IN_PROGRESS);
+        if (self->ith_state == MACH_MSG_SUCCESS) {
+            self->ith_state = MACH_MSG_SUCCESS; // veya temiz durum sıfırlaması
+            continue;
+        }
+        assert(self->ith_state == MACH_SEND_IN_PROGRESS);
 
-		/* take ourselves off blocked queue */
+        /* take ourselves off blocked queue under port lock */
+        ipc_thread_rmqueue(&port->ip_blocked, self);
+        
+        /* [DEFENSIVE]: Clear state to prevent stale status reuse */
+        self->ith_state = MACH_MSG_SUCCESS;
 
-		ipc_thread_rmqueue(&port->ip_blocked, self);
+        /*
+         *  Thread wakeup-reason field tells us why
+         *  the wait was interrupted.
+         */
 
-		/*
-		 *	Thread wakeup-reason field tells us why
-		 *	the wait was interrupted.
-		 */
+        switch (self->ith_wait_result) {
+            case THREAD_INTERRUPTED:
+            /* send was interrupted - give up */
 
-		switch (self->ith_wait_result) {
-		    case THREAD_INTERRUPTED:
-			/* send was interrupted - give up */
+            ip_unlock(port);
+            return MACH_SEND_INTERRUPTED;
 
-			ip_unlock(port);
-			return MACH_SEND_INTERRUPTED;
+            case THREAD_TIMED_OUT:
+            /* timeout expired */
 
-		    case THREAD_TIMED_OUT:
-			/* timeout expired */
-
-			assert(option & MACH_SEND_TIMEOUT);
-			time_out = 0;
-			break;
+            assert(option & MACH_SEND_TIMEOUT);
+            time_out = 0;
+            break;
 
-		    case THREAD_RESTART:
-		    default:
+            case THREAD_RESTART:
+            default:
 #if MACH_ASSERT
-			assert(!"ipc_mqueue_send");
+            assert(!"ipc_mqueue_send: unexpected thread wakeup result");
 #else
-			panic("ipc_mqueue_send");
+            panic("ipc_mqueue_send");
 #endif
-		}
-	}
+        }
+    }
 
 	if (kmsg->ikm_header.msgh_bits & MACH_MSGH_BITS_CIRCULAR) {
 		ip_unlock(port);