lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 08 Oct 2007 17:46:26 -0500
From:	Steve Wise <>
To:	David Miller <>
Subject: Re: pktgen question

David Miller wrote:
> From: Ben Greear <>
> Date: Mon, 08 Oct 2007 14:57:13 -0700
>> This skb recycling can certainly work and has been done several
>> times before.  It never gets into the kernel though.
> Because it doesn't work.
> A socket can hang onto a receive packet essentially forever.
> You cannot therefore rely upon the network stack to give you the
> packet back in some reasonable finite amount of time.  This is simply
> the nature of the beast.
> Which means that you either:
> 1) Starve and stop receiving packets when the recycling ring
>    runs out because all of those packets are stuck in socket
>    buffers.  This is easily DoS'able by users on your system
> 2) End up allocating new packets anyways, but then what's the
>    point of the recycling ring?  It's just a hack that works
>    when everything goes as planned, and in real life that is
>    rarely the case.
> It also makes the driver locking more complicated.  Packet
> input occurs in NAPI drivers via netif_receive_skb() which
> would be capable of recycling packets back to the same
> driver in a recycling scheme.  But the recycling can occur
> from other contexts too.  The netif_receive_skb() caller
> already has atomic access to the receive queue, but those
> other callback cases do not.
> That locking issue is just the tip of the iceberg.  Once you
> start discussing solutions, all sorts of new issues begin to
> pop up.
> SKB recycling, just say no.

We're talking about just for

To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to
More majordomo info at

Powered by blists - more mailing lists