Re: hwmon: (sis5595) potential null pointer dereference in probe

From: Evgeny Novikov
Date: Tue Aug 04 2020 - 10:49:16 EST

04.08.2020, 17:33, "Guenter Roeck" <linux@xxxxxxxxxxxx>:
> On 8/4/20 4:50 AM, Evgeny Novikov wrote:
>>  sis5595_pci_probe() registers platform driver callbacks and just then
>>  initializes global pointer variable s_bridge. sis5595_probe() may
>>  dereference it before this happens that can result in null pointer
>>  dereference.
> sis5595_probe() is only called after the device is registered,
> which happens in sis5595_device_add() after s_bridge is set. This is
> a southbridge, so there won't be any hot insertion/removal events.

Thank you for this hint. We need to tune our models appropriately.

>>  We can not swap registration of platform driver callbacks with
>>  initialization of s_bridge since sm_sis5595_exit() assumes the
>>  current order. Perhaps it has sense to implement a pci_driver.remove
>>  callback that will take care about deregistration of platform driver
>>  callbacks.
> Agreed regarding the remove function. However, given the age of the chip,
> I'd rather remove the driver than spending time on cleanup efforts.
> This looks like a perfect candidate for depreciation.

This is completely up to you. Anyway the driver does not have the bug.

Best regards,

> Guenter