Hi,
On 2/28/23 11:05, Heikki Krogerus wrote:
> On Tue, Feb 28, 2023 at 10:03:03AM +0100, Hans de Goede wrote:
>> When ucsi_init() fails, ucsi->connector is NULL, yet in case of
>> ucsi_acpi we may still get events which cause the ucs_acpi code to call
>> ucsi_connector_change(), which then derefs the NULL ucsi->connector
>> pointer.
>>
>> Fix this by adding a check for ucsi->connector being NULL, as is
>> already done in ucsi_resume() for similar reasons.
>>
>> Fixes: bdc62f2bae8f ("usb: typec: ucsi: Simplified registration and I/O API")
>> Cc: stable@xxxxxxxxxxxxxxx
>> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
>> ---
>> drivers/usb/typec/ucsi/ucsi.c | 8 +++++++-
>> 1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
>> index 1cf8947c6d66..e762897cb25a 100644
>> --- a/drivers/usb/typec/ucsi/ucsi.c
>> +++ b/drivers/usb/typec/ucsi/ucsi.c
>> @@ -842,7 +842,13 @@ static void ucsi_handle_connector_change(struct work_struct *work)
>> */
>> void ucsi_connector_change(struct ucsi *ucsi, u8 num)
>> {
>> - struct ucsi_connector *con = &ucsi->connector[num - 1];
>> + struct ucsi_connector *con;
>> +
>> + /* Check for ucsi_init() failure */
>> + if (!ucsi->connector)
>> + return;
>> +
>> + con = &ucsi->connector[num - 1];
>>
>> if (!(ucsi->ntfy & UCSI_ENABLE_NTFY_CONNECTOR_CHANGE)) {
>> dev_dbg(ucsi->dev, "Bogus connector change event\n");
>
> I think we should try to rely on that ucsi->ntfy. Would this work:
>
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index fe1963e328378..0da1e9c66971a 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -928,15 +928,13 @@ static void ucsi_handle_connector_change(struct work_struct *work)
> */
> void ucsi_connector_change(struct ucsi *ucsi, u8 num)
> {
> - struct ucsi_connector *con = &ucsi->connector[num - 1];
> -
> if (!(ucsi->ntfy & UCSI_ENABLE_NTFY_CONNECTOR_CHANGE)) {
> dev_dbg(ucsi->dev, "Bogus connector change event\n");
> return;
> }
>
> if (!test_and_set_bit(EVENT_PENDING, &ucsi->flags))
> - schedule_work(&con->work);
> + schedule_work(&ucsi->connector[num - 1].work);
> }
> EXPORT_SYMBOL_GPL(ucsi_connector_change);
>
This hunk is not necessary, the con pointer pointing to lala land is
not an issue as long as we don't deref it. The &ucsi->connector[num - 1];
does not deref ucsi->connector it it simply adds an offset to it and
stores that in con (the backtrace I got pointed to the schedule_work call).
But I guess your way does make it more obvious that we don't
deref ucsi->connector.
> @@ -1404,6 +1402,7 @@ static int ucsi_init(struct ucsi *ucsi)
> ucsi->connector = NULL;
>
> err_reset:
> + ucsi->ntfy = 0;
> memset(&ucsi->cap, 0, sizeof(ucsi->cap));
> ucsi_reset_ppm(ucsi);
> err:
In would expect this to fix things, but I only have access to the monitor
triggering this on Mondays, so I can only 100% confirm next Monday.
Note this does open the race I try to fix in patch 2/3 again.
So what should be done here is to make ntfy a local variable and only
store it in ucsi->ntfy on success.
Regards,
Hans
