linux-kernel - Re: KASAN: use-after-free Read in addr

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Date:   Mon, 29 Jun 2020 19:27:40 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Jason Gunthorpe <jgg@...pe.ca>,
        syzkaller <syzkaller@...glegroups.com>
Cc:     Hillf Danton <hdanton@...a.com>,
        syzbot <syzbot+a929647172775e335941@...kaller.appspotmail.com>,
        chuck.lever@...cle.com, Doug Ledford <dledford@...hat.com>,
        Leon Romanovsky <leon@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        RDMA mailing list <linux-rdma@...r.kernel.org>,
        parav@...lanox.com, Markus Elfring <Markus.Elfring@....de>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>
Subject: Re: KASAN: use-after-free Read in addr_handler (2)

On Mon, Jun 29, 2020 at 4:42 PM Dmitry Vyukov <dvyukov@...gle.com> wrote:
>
> On Sun, Jun 28, 2020 at 12:25 AM Jason Gunthorpe <jgg@...pe.ca> wrote:
> >
> > On Sat, Jun 27, 2020 at 09:02:05PM +0800, Hillf Danton wrote:
> > > > So, to hit this syzkaller one of these must have happened:
> > > >  1) rdma_addr_cancel() didn't work and the process_one_work() is still
> > > >     runnable/running
> > >
> > > What syzbot reported indicates that the kworker did survive not only
> > > canceling work but the handler_mutex, despite it's a sync cancel that
> > > waits for the work to complete.
> >
> > The syzbot report doesn't confirm that the cancel work was actaully
> > called.
> >
> > The most likely situation is that it was skipped because of the state
> > mangling the patch fixes..
> >
> > > >  2) The state changed away from RDMA_CM_ADDR_QUERY without doing
> > > >     rdma_addr_cancel()
> > >
> > > The cancel does cover the query state in the reported case, and have
> > > difficult time working out what's in the patch below preventing the
> > > work from going across the line the sync cancel draws. That's the
> > > question we can revisit once there is a reproducer available.
> >
> > rdma-cm never seems to get reproducers from syzkaller
>
> +syzkaller mailing list
>
> Hi Jason,
>
> Wonder if there is some systematic issue. Let me double check.

By scanning bugs at:
https://syzkaller.appspot.com/upstream
https://syzkaller.appspot.com/upstream/fixed

I found a significant number of bugs that I would qualify as "rdma-cm"
and that have reproducers. Here is an incomplete list (I did not get
to the end):

https://syzkaller.appspot.com/bug?id=b8febdb3c7c8c1f1b606fb903cee66b21b2fd02f
https://syzkaller.appspot.com/bug?id=d5222b3e1659e0aea19df562c79f216515740daa
https://syzkaller.appspot.com/bug?id=c600e111223ce0a20e5f2fb4e9a4ebdff54d7fa6
https://syzkaller.appspot.com/bug?id=a9796acbdecc1b2ba927578917755899c63c48af
https://syzkaller.appspot.com/bug?id=95f89b8fb9fdc42e28ad586e657fea074e4e719b
https://syzkaller.appspot.com/bug?id=8dc0bcd9dd6ec915ba10b3354740eb420884acaa
https://syzkaller.appspot.com/bug?id=805ad726feb6910e35088ae7bbe61f4125e573b7
https://syzkaller.appspot.com/bug?id=56b60fb3340c5995373fe5b8eae9e8722a012fc4
https://syzkaller.appspot.com/bug?id=38d36d1b26b4299bf964d50af4d79688d39ab960
https://syzkaller.appspot.com/bug?id=25e00dd59f31783f233185cb60064b0ab645310f
https://syzkaller.appspot.com/bug?id=2f38d7e5312fdd0acc979c5e26ef2ef8f3370996

Do you mean some specific subset of bugs by "rdma-cm"? If yes, what is
that subset?