From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Magnus Karlsson <magnus.karlsson@gmail.com>
Cc: "Jonathan Lemon" <jonathan.lemon@gmail.com>,
"Magnus Karlsson" <magnus.karlsson@intel.com>,
"Björn Töpel" <bjorn.topel@intel.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Network Development" <netdev@vger.kernel.org>,
"Kal Cutter Conley" <kal.conley@dectris.com>,
bpf <bpf@vger.kernel.org>
Subject: Re: [PATCH bpf] xsk: fix registration of Rx-only sockets
Date: Thu, 24 Oct 2019 08:19:30 -0700 [thread overview]
Message-ID: <CAADnVQKYME2GgSPs_DTS97c05BT=L49KJ+XUXEStgK5Sg3UOmA@mail.gmail.com> (raw)
In-Reply-To: <CAJ8uoz2FDkygCG5myz_OzAPHSiCPGR1Y-OHEi6xNjQEHoAia8w@mail.gmail.com>
On Thu, Oct 24, 2019 at 5:53 AM Magnus Karlsson
<magnus.karlsson@gmail.com> wrote:
>
> On Thu, Oct 24, 2019 at 12:47 PM Jonathan Lemon
> <jonathan.lemon@gmail.com> wrote:
> >
> > On 21 Oct 2019, at 1:16, Magnus Karlsson wrote:
> >
> > > Having Rx-only AF_XDP sockets can potentially lead to a crash in the
> > > system by a NULL pointer dereference in xsk_umem_consume_tx(). This
> > > function iterates through a list of all sockets tied to a umem and
> > > checks if there are any packets to send on the Tx ring. Rx-only
> > > sockets do not have a Tx ring, so this will cause a NULL pointer
> > > dereference. This will happen if you have registered one or more
> > > Rx-only sockets to a umem and the driver is checking the Tx ring even
> > > on Rx, or if the XDP_SHARED_UMEM mode is used and there is a mix of
> > > Rx-only and other sockets tied to the same umem.
> > >
> > > Fixed by only putting sockets with a Tx component on the list that
> > > xsk_umem_consume_tx() iterates over.
> >
> > A future improvement might be renaming umem->xsk_list to umem->xsk_tx_list
> > or similar, in order to make it clear that the list is only used on the
> > TX path.
>
> Agreed. Had that exact name in my first internal version of the patch
> :-), but that rename touched a lot of places so it obfuscated the fix
> and therefore I removed it to make it clearer. But I can submit a
> patch with the rename to bpf-next.
please do so after bpf fixes will travel to net->linus->net-next->bpf-next
Dealing with merge conflicts is not worth it otherwise.
prev parent reply other threads:[~2019-10-24 15:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-21 8:16 [PATCH bpf] xsk: fix registration of Rx-only sockets Magnus Karlsson
2019-10-23 23:03 ` Jonathan Lemon
2019-10-24 3:22 ` Alexei Starovoitov
2019-10-24 12:53 ` Magnus Karlsson
2019-10-24 15:19 ` Alexei Starovoitov [this message]
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