Re: [PATCH v3] usb: typec: tcpm: Check for port partner validity before consuming it

[Dmitry Baryshkov]

On Sat, Apr 27, 2024 at 08:28:12PM +0000, Badhri Jagan Sridharan wrote:
> typec_register_partner() does not guarantee partner registration
> to always succeed. In the event of failure, port->partner is set
> to the error value or NULL. Given that port->partner validity is
> not checked, this results in the following crash:
> 
> Unable to handle kernel NULL pointer dereference at virtual address xx
>  pc : run_state_machine+0x1bc8/0x1c08
>  lr : run_state_machine+0x1b90/0x1c08
> ..
>  Call trace:
>    run_state_machine+0x1bc8/0x1c08
>    tcpm_state_machine_work+0x94/0xe4
>    kthread_worker_fn+0x118/0x328
>    kthread+0x1d0/0x23c
>    ret_from_fork+0x10/0x20
> 
> To prevent the crash, check for port->partner validity before
> derefencing it in all the call sites.
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: c97cd0b4b54e ("usb: typec: tcpm: set initial svdm version based on pd revision")
> Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>
> ---
>  drivers/usb/typec/tcpm/tcpm.c | 30 +++++++++++++++++++++++-------
>  1 file changed, 23 insertions(+), 7 deletions(-)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>


-- 
With best wishes
Dmitry