On Wed, 18 Mar 2026, Gui-Dong Han <[email protected]> wrote: > Passing NULL to debugfs_create_str() causes a NULL pointer dereference > upon reading, and is no longer permitted. Change the default values of > dmc_firmware_path and vbt_firmware to empty strings (""). > > Existing code that consumes these parameters already verifies both > pointer validity and string length, so empty strings are handled > correctly. Furthermore, heap allocation is not required here: these > debugfs parameters are created with strictly read-only permissions > (0400). As a result, the debugfs write operation is never invoked, > meaning the static empty string will not be erroneously freed by > kfree(). > > Fixes: e9913f0bd2e1 ("drm/i915/display: move dmc_firmware_path to display > params") > Fixes: 29292bc6cc37 ("drm/i915/display: Move vbt_firmware module parameter > under display") > Signed-off-by: Gui-Dong Han <[email protected]> > --- > drivers/gpu/drm/i915/display/intel_display_params.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_display_params.h > b/drivers/gpu/drm/i915/display/intel_display_params.h > index b95ecf728daa..0a8cad98d480 100644 > --- a/drivers/gpu/drm/i915/display/intel_display_params.h > +++ b/drivers/gpu/drm/i915/display/intel_display_params.h > @@ -23,8 +23,8 @@ struct drm_printer; > * debugfs file > */ > #define INTEL_DISPLAY_PARAMS_FOR_EACH(param) \ > - param(char *, dmc_firmware_path, NULL, 0400) \ > - param(char *, vbt_firmware, NULL, 0400) \ > + param(char *, dmc_firmware_path, "", 0400) \ > + param(char *, vbt_firmware, "", 0400) \
Admittedly this is all very convoluted, but these NULL pointers (or pointers to them) are never passed to debugfs_create_str(). BR, Jani. > param(int, lvds_channel_mode, 0, 0400) \ > param(int, panel_use_ssc, -1, 0600) \ > param(int, vbt_sdvo_panel_type, -1, 0400) \ -- Jani Nikula, Intel
