netdev - Re: [PATCH net] VSOCK: check sk state before receive

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Date:   Wed, 13 Jun 2018 09:44:02 +0800
From:   Hangbin Liu <liuhangbin@...il.com>
To:     "Jorgen S. Hansen" <jhansen@...are.com>
Cc:     Stefan Hajnoczi <stefanha@...hat.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH net] VSOCK: check sk state before receive

On Mon, Jun 04, 2018 at 04:02:39PM +0000, Jorgen S. Hansen wrote:
> 
> > On May 30, 2018, at 11:17 AM, Stefan Hajnoczi <stefanha@...hat.com> wrote:
> > 
> > On Sun, May 27, 2018 at 11:29:45PM +0800, Hangbin Liu wrote:
> >> Hmm...Although I won't reproduce this bug with my reproducer after
> >> apply my patch. I could still get a similiar issue with syzkaller sock vnet test.
> >> 
> >> It looks this patch is not complete. Here is the KASAN call trace with my patch.
> >> I can also reproduce it without my patch.
> > 
> > Seems like a race between vmci_datagram_destroy_handle() and the
> > delayed callback, vmci_transport_recv_dgram_cb().
> > 
> > I don't know the VMCI transport well so I'll leave this to Jorgen.
> 
> Yes, it looks like we are calling the delayed callback after we return from vmci_datagram_destroy_handle(). I’ll take a closer look at the VMCI side here - the refcounting of VMCI datagram endpoints should guard against this, since the delayed callback does a get on the datagram resource, so this could a VMCI driver issue, and not a problem in the VMCI transport for AF_VSOCK.

Hi Jorgen,

Thanks for helping look at this. I'm happy to run test for you patch.

Thanks
Hangbin