On (24/10/31 13:33), Jani Nikula wrote: > > intel_ddi_init() may skip connector initialization, for instance, > > both intel_ddi_init_dp_connector() and intel_ddi_init_hdmi_connector() > > are optional. This leads to situation that ->attached_connector may > > be NULL for some connectors. For instance, on my setup 'DDI A/PHY A' > > and 'DDI TC1/PHY TC1' are not initialized. > > > > However, functions like intel_dp_dual_mode_set_tmds_output() and > > friends don't take this into consideration. This leads to NULL > > ptr-derefs: > > > > KASAN: null-ptr-deref in range [0x0000000000000848-0x000000000000084f] > > RIP: 0010:intel_hdmi_encoder_shutdown+0x105/0x230 > > Call Trace: > > <TASK> > > i915_driver_shutdown+0x2d8/0x490 > > pci_device_shutdown+0x83/0x150 > > device_shutdown+0x4ad/0x660 > > __se_sys_reboot+0x29c/0x4d0 > > do_syscall_64+0x60/0x90 > > > > Add a new helper to avoid NULL ->attached_connector derefs and > > switch some intel_hdmi function to it. I'm not sure if we need > > to switch all or just intel_dp_dual_mode_set_tmds_output() (I > > have only seen this one doing NULL derefs so far). > > I think the question is, what are we doing running this code if the > connector initialization was skipped? I'm not in position to answer that question, I guess it wasn't even asked to me. But... For instance, intel_ddi_init_hdmi_connector()->intel_hdmi_init_connector() can "error out" and leave ->attached_connector NULL; I can count 3 conditional returns before `->attached_connector = intel_connector` assignment, yet none of the upper functions would even know, because intel_hdmi_init_connector() returns void. And this is not the only case. So there are several ways to have ->attached_connector == NULL.
