netdev - Re: [net-next PATCH] bpf: cpumap fix potential lost wake-up problem

lists.openwall.net		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 linux-cve-announce 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:   Tue, 24 Oct 2017 06:46:32 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     netdev@...r.kernel.org, "Michael S. Tsirkin" <mst@...hat.com>,
        Rik van Riel <riel@...hat.com>,
        Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        brouer@...hat.com
Subject: Re: [net-next PATCH] bpf: cpumap fix potential lost wake-up problem

On Mon, 23 Oct 2017 22:34:37 +0200
Daniel Borkmann <daniel@...earbox.net> wrote:

> On 10/23/2017 07:39 PM, Jesper Dangaard Brouer wrote:
> > As pointed out by Michael, commit 1c601d829ab0 ("bpf: cpumap xdp_buff
> > to skb conversion and allocation") contains a classical example of the
> > potential lost wake-up problem.
> >
> > We need to recheck the condition __ptr_ring_empty() after changing
> > current->state to TASK_INTERRUPTIBLE, this avoids a race between
> > wake_up_process() and schedule(). After this, a race with
> > wake_up_process() will simply change the state to TASK_RUNNING, and
> > the schedule() call not really put us to sleep.
> >
> > Fixes: 1c601d829ab0 ("bpf: cpumap xdp_buff to skb conversion and allocation")
> > Reported-by: "Michael S. Tsirkin" <mst@...hat.com>  
> 
> SOB missing ...

Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>

Damn... DaveM do I need to resubmit? Or will patchwork pickup above SOB?

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer