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Date:   Thu, 19 Oct 2023 11:23:33 +0300
From:   Heikki Krogerus <heikki.krogerus@linux.intel.com>
To:     Jimmy Hu <hhhuuu@google.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
Subject: Re: [PATCH] usb: typec: tcpm: Fix NULL pointer dereference in
 tcpm_pd_svdm()
Message-ID: <ZTDnhbYDq7kq8vBj@kuha.fi.intel.com>
References: <20231019060616.1988631-1-hhhuuu@google.com>
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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...?

> ---
>  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/tcpm.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, struct typec_altmode *adev,
>  			if (PD_VDO_VID(p[0]) != 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->partner,
>  							       PD_VDO_SVDM_VER(p[0]));

-- 
heikki