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

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Date:   Thu, 21 Nov 2019 13:44:14 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     john.fastabend@...il.com
Cc:     alexei.starovoitov@...il.com, netdev@...r.kernel.org,
        dan.carpenter@...cle.com, daniel@...earbox.net
Subject: Re: [net PATCH] bpf: skmsg, fix potential psock NULL pointer
 dereference

From: John Fastabend <john.fastabend@...il.com>
Date: Thu, 21 Nov 2019 12:27:23 -0800

> 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.

Applied to net-next, thanks.