NDIS IM Memory Leak

NTDEV
1

I have a NDIS IM that modifies packets both incoming and outgoing. Eventually I get
an error on the send side from the NdisAllocateMemoryWithTag call. After much debugging, I have not found any problems with the code that allocs/frees new packets, buffers and VM. So, here is my question:

Is it possible to incorrectly set values in the original or new packet (OOB, per packet, etc) that could cause another layer to leak memory. I do not access the buffer chain in the original packets.

I hope I have provided enough info…

2

> Is it possible to incorrectly set values in the original or new packet (OOB, per

packet, etc) that could cause another layer to leak memory.

Of course…

The very first example that comes to my mind is setting NDIS_STATUS_RESOURCES in a new packet that you don’t free immediately after indication - if NDIS_STATUS_RESOURCES is set, this packet will never get returned to your MPReturnPacket(), because bound protocols will make their own copies of it, and, hence, are not going to call NdisReturnPacket() with it. Therefore, if you free packets only in MPReturnPacket(), indicating a new packet with NDIS_STATUS_RESOURCES inevitably leads to a memory leak…

Anton Bassov

3

> -----Original Message-----

From: xxxxx@lists.osr.com [mailto:bounce-300228-
xxxxx@lists.osr.com] On Behalf Of xxxxx@socket.net
Sent: Wednesday, September 12, 2007 6:03 PM
To: Windows System Software Devs Interest List
Subject: [ntdev] NDIS IM Memory Leak

I have a NDIS IM that modifies packets both incoming and outgoing.
Eventually I get
an error on the send side from the NdisAllocateMemoryWithTag call.
After much debugging, I have not found any problems with the code that
allocs/frees new packets, buffers and VM. So, here is my question:

Is it possible to incorrectly set values in the original or new packet
(OOB, per packet, etc) that could cause another layer to leak memory.
I do not access the buffer chain in the original packets.

I hope I have provided enough info…
[PCAUSA] Key things to look at include returning original packet to the originator. Do you call NdisMReturnPacket on original send packets?

Also, in ProtocolSendComplete do you differentiate between your own packets being completed and Passthru (unmodified) packets - if you have any. You should not call NdisMReturnPacket for your modified packets.

The “original packet” field in your modified packet should point to your own packet - not the original packet.

Can’t think of much else. Somewhere you have overlooked releasing something that you allocated. The fault could be elsewhere than the send path. For example, the receive path could be screwed-up, but the fault finally shows up when you try to make a send.

Take a look at the NDIS debugger extension. Perhaps it has a tool that can show memory hog.

Have you used the pooltag tools to see if, in fact, it is your own allocations that are not being released. That’s what the TAG is for!

Good luck,

Thomas F. Divine
http://www.pcausa.com

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4

From : Thomas F. Divine
To : Windows System Software Devs Interest List
Subject : RE: [ntdev] NDIS IM Memory Leak
Date : Wed, 12 Sep 2007 18:20:58 -0400
>
>
> > -----Original Message-----
> > From: xxxxx@lists.osr.com [mailto:bounce-300228-
> > xxxxx@lists.osr.com] On Behalf Of xxxxx@socket.net
> > Sent: Wednesday, September 12, 2007 6:03 PM
> > To: Windows System Software Devs Interest List
> > Subject: [ntdev] NDIS IM Memory Leak
> >
> > I have a NDIS IM that modifies packets both incoming and outgoing.
> > Eventually I get
> > an error on the send side from the NdisAllocateMemoryWithTag call.
> > After much debugging, I have not found any problems with the code that
> > allocs/frees new packets, buffers and VM. So, here is my question:
> >
> > Is it possible to incorrectly set values in the original or new packet
> > (OOB, per packet, etc) that could cause another layer to leak memory.
> > I do not access the buffer chain in the original packets.
> >
> > I hope I have provided enough info…
> [PCAUSA] Key things to look at include returning original packet to the
originator. Do you call NdisMReturnPacket on original send packets?

I call NdisMSendComplete for original send packets. Is that what you
meant?

5

> -----Original Message-----

From: xxxxx@lists.osr.com [mailto:bounce-300237-
xxxxx@lists.osr.com] On Behalf Of xxxxx@socket.net
Sent: Wednesday, September 12, 2007 6:56 PM
To: Windows System Software Devs Interest List
Subject: Re: RE: [ntdev] NDIS IM Memory Leak

>From : Thomas F. Divine
> To : Windows System Software Devs Interest List
> Subject : RE: [ntdev] NDIS IM Memory Leak
> Date : Wed, 12 Sep 2007 18:20:58 -0400
> >
> >
> > > -----Original Message-----
> > > From: xxxxx@lists.osr.com [mailto:bounce-300228-
> > > xxxxx@lists.osr.com] On Behalf Of xxxxx@socket.net
> > > Sent: Wednesday, September 12, 2007 6:03 PM
> > > To: Windows System Software Devs Interest List
> > > Subject: [ntdev] NDIS IM Memory Leak
> > >
> > > I have a NDIS IM that modifies packets both incoming and outgoing.
> > > Eventually I get
> > > an error on the send side from the NdisAllocateMemoryWithTag call.
> > > After much debugging, I have not found any problems with the code
> that
> > > allocs/frees new packets, buffers and VM. So, here is my question:
> > >
> > > Is it possible to incorrectly set values in the original or new
> packet
> > > (OOB, per packet, etc) that could cause another layer to leak
> memory.
> > > I do not access the buffer chain in the original packets.
> > >
> > > I hope I have provided enough info…
> > [PCAUSA] Key things to look at include returning original packet to
> the
> originator. Do you call NdisMReturnPacket on original send packets?
>
> I call NdisMSendComplete for original send packets. Is that what you
> meant?
[PCAUSA] Yep!

Thomas F. Divine