netdev - Re: [net PATCH] bpf: skmsg, fix potential psock NULL pointer dereference

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Date:   Thu, 21 Nov 2019 12:27:23 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        John Fastabend <john.fastabend@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Network Development <netdev@...r.kernel.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: Re: [net PATCH] bpf: skmsg, fix potential psock NULL pointer
 dereference

Alexei Starovoitov wrote:
> On Thu, Nov 21, 2019 at 8:28 AM John Fastabend <john.fastabend@...il.com> wrote:
> >
> > Report from Dan Carpenter,
> >
> >  net/core/skmsg.c:792 sk_psock_write_space()
> >  error: we previously assumed 'psock' could be null (see line 790)
> >
> >  net/core/skmsg.c
> >    789 psock = sk_psock(sk);
> >    790 if (likely(psock && sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)))
> >  Check for NULL
> >    791 schedule_work(&psock->work);
> >    792 write_space = psock->saved_write_space;
> >                      ^^^^^^^^^^^^^^^^^^^^^^^^
> >    793          rcu_read_unlock();
> >    794          write_space(sk);
> >
> > Ensure psock dereference on line 792 only occurs if psock is not null.
> >
> > Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> > Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
> > Signed-off-by: John Fastabend <john.fastabend@...il.com>
> 
> lgtm.
> John, do you feel strongly about it going to net tree asap?
> Can it go to net-next ? The merge window is right around the corner.

Agree we can send it to net-next, its been in the kernel for multiple
versions anyways.