Index: drivers/usb/usbehci/usb_request.cpp
===================================================================
--- drivers/usb/usbehci/usb_request.cpp	(revision 70507)
+++ drivers/usb/usbehci/usb_request.cpp	(working copy)
@@ -842,6 +842,7 @@
         //
         // failed to allocate queue head
         //
+        DPRINT1("[EHCI] Failed to create queue head\n");
         return STATUS_INSUFFICIENT_RESOURCES;
     }
 
@@ -856,10 +857,11 @@
     Status = BuildSetupPacket();
     if (!NT_SUCCESS(Status))
     {
-        //
-        // failed to allocate setup packet
-        //
-        ASSERT(FALSE);
+        // failed to create setup packet
+        DPRINT1("[EHCI] Failed to create setup packet\n");
+
+        //release queue head
+        m_DmaManager->Release(QueueHead, sizeof(QUEUE_HEAD));
         return STATUS_INSUFFICIENT_RESOURCES;
     }
 
@@ -869,10 +871,17 @@
     Status = CreateDescriptor(&SetupDescriptor);
     if (!NT_SUCCESS(Status))
     {
-        //
-        // failed to allocate transfer descriptor
-        //
-        ASSERT(FALSE);
+        // failed to create setup transfer descriptor
+        DPRINT1("[EHCI] Failed to create setup descriptor\n");
+
+        if (m_DescriptorPacket)
+        {
+            // release packet descriptor
+            m_DmaManager->Release(m_DescriptorPacket, sizeof(USB_DEFAULT_PIPE_SETUP_PACKET));
+        }
+
+        // release queue head
+        m_DmaManager->Release(QueueHead, sizeof(QUEUE_HEAD));
         return Status;
     }
 
@@ -882,10 +891,20 @@
     Status = CreateDescriptor(&StatusDescriptor);
     if (!NT_SUCCESS(Status))
     {
-        //
-        // failed to allocate transfer descriptor
-        //
-        ASSERT(FALSE);
+        // failed to create status transfer descriptor
+        DPRINT1("[EHCI] Failed to create status descriptor\n");
+
+        // release setup transfer descriptor
+        m_DmaManager->Release(SetupDescriptor, sizeof(QUEUE_TRANSFER_DESCRIPTOR));
+
+        if (m_DescriptorPacket)
+        {
+            // release packet descriptor
+            m_DmaManager->Release(m_DescriptorPacket, sizeof(USB_DEFAULT_PIPE_SETUP_PACKET));
+        }
+
+        // release queue head
+        m_DmaManager->Release(QueueHead, sizeof(QUEUE_HEAD));
         return Status;
     }
 
@@ -929,10 +948,28 @@
                                               NULL,
                                               &DescriptorChainLength);
 
-        //
-        // FIXME handle errors
-        //
-        ASSERT(Status == STATUS_SUCCESS);
+        if (!NT_SUCCESS(Status))
+        {
+            // failed to create descriptor chain
+            DPRINT1("[EHCI] Failed to create status descriptor\n");
+
+            // release status transfer descriptor
+            m_DmaManager->Release(StatusDescriptor, sizeof(QUEUE_TRANSFER_DESCRIPTOR));
+
+            // release setup transfer descriptor
+            m_DmaManager->Release(SetupDescriptor, sizeof(QUEUE_TRANSFER_DESCRIPTOR));
+
+            if (m_DescriptorPacket)
+            {
+                // release packet descriptor
+                m_DmaManager->Release(m_DescriptorPacket, sizeof(USB_DEFAULT_PIPE_SETUP_PACKET));
+            }
+
+            // release queue head
+            m_DmaManager->Release(QueueHead, sizeof(QUEUE_HEAD));
+            return Status;
+        }
+
         if (m_TransferBufferLength != DescriptorChainLength)
         {
             DPRINT1("DescriptorChainLength %x\n", DescriptorChainLength);
Index: drivers/usb/usbohci/usb_request.cpp
===================================================================
--- drivers/usb/usbohci/usb_request.cpp	(revision 70507)
+++ drivers/usb/usbohci/usb_request.cpp	(working copy)
@@ -1289,6 +1289,15 @@
                                           &LastDescriptor,
                                           &ChainDescriptorLength);
 
+    if (!NT_SUCCESS(Status))
+    {
+        //
+        // failed to build transfer descriptor chain
+        //
+        m_DmaManager->Release(EndpointDescriptor, sizeof(OHCI_ENDPOINT_DESCRIPTOR));
+        return Status;
+    }
+
     //
     // move to next offset
     //
Index: drivers/usb/usbuhci/usb_request.cpp
===================================================================
--- drivers/usb/usbuhci/usb_request.cpp	(revision 70507)
+++ drivers/usb/usbuhci/usb_request.cpp	(working copy)
@@ -1041,6 +1041,16 @@
                                           &ChainDescriptorLength,
                                            NULL);
 
+    if (!NT_SUCCESS(Status))
+    {
+        //
+        // failed to allocate descriptor
+        //
+        DPRINT1("[UHCI] Failed to create descriptor chain\n");
+        m_DmaManager->Release(QueueHead, sizeof(UHCI_QUEUE_HEAD));
+        return Status;
+    }
+
     // adjust buffer offset
     m_TransferBufferLengthCompleted += ChainDescriptorLength;