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References: <20231019060616.1988631-1-hhhuuu@google.com> <ZTDnhbYDq7kq8vBj@kuha.fi.intel.com>
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From:   Jimmy Hu <hhhuuu@google.com>
Date:   Fri, 20 Oct 2023 09:24:53 +0800
Message-ID: <CAJh=zjLtFmO4FWn8gzWWNQbfVggiq-K3O_WOcf=OV_ucybD7Yw@mail.gmail.com>
Subject: Re: [PATCH] usb: typec: tcpm: Fix NULL pointer dereference in tcpm_pd_svdm()
To:     Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc:     linux@roeck-us.net, gregkh@linuxfoundation.org, kyletso@google.com,
        badhri@google.com, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Thu, Oct 19, 2023 at 4:24=E2=80=AFPM Heikki Krogerus
<heikki.krogerus@linux.intel.com> wrote:
>
> On Thu, Oct 19, 2023 at 06:06:16AM +0000, Jimmy Hu wrote:
> > It is possible that typec_register_partner() returns ERR_PTR on failure=
.
> > When port->partner is an error, a NULL pointer dereference may occur as
> > shown below.
> >
> > [91222.095236][  T319] typec port0: failed to register partner (-17)
> > ...
> > [91225.061491][  T319] Unable to handle kernel NULL pointer dereference
> > at virtual address 000000000000039f
> > [91225.274642][  T319] pc : tcpm_pd_data_request+0x310/0x13fc
> > [91225.274646][  T319] lr : tcpm_pd_data_request+0x298/0x13fc
> > [91225.308067][  T319] Call trace:
> > [91225.308070][  T319]  tcpm_pd_data_request+0x310/0x13fc
> > [91225.308073][  T319]  tcpm_pd_rx_handler+0x100/0x9e8
> > [91225.355900][  T319]  kthread_worker_fn+0x178/0x58c
> > [91225.355902][  T319]  kthread+0x150/0x200
> > [91225.355905][  T319]  ret_from_fork+0x10/0x30
> >
> > Add a check for port->partner to avoid dereferencing a NULL pointer.
> >
> > Fixes: 5e1d4c49fbc8 ("usb: typec: tcpm: Determine common SVDM Version")
> > Signed-off-by: Jimmy Hu <hhhuuu@google.com>
>
> No CC stable...?
Added in patch v2.
>
> > ---
> >  drivers/usb/typec/tcpm/tcpm.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcp=
m.c
> > index 6e843c511b85..792ec4ac7d8d 100644
> > --- a/drivers/usb/typec/tcpm/tcpm.c
> > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > @@ -1625,6 +1625,9 @@ static int tcpm_pd_svdm(struct tcpm_port *port, s=
truct typec_altmode *adev,
> >                       if (PD_VDO_VID(p[0]) !=3D USB_SID_PD)
> >                               break;
> >
> > +                     if (IS_ERR_OR_NULL(port->partner))
> > +                             break;
> > +
> >                       if (PD_VDO_SVDM_VER(p[0]) < svdm_version) {
> >                               typec_partner_set_svdm_version(port->part=
ner,
> >                                                              PD_VDO_SVD=
M_VER(p[0]));
>
> --
> heikki