On Wed, Dec 07, 2022 at 09:59:04PM +0800, Robin Murphy wrote: >> As kzalloc may fail and return NULL pointer, it should be better to check >> the return value in order to avoid the NULL pointer dereference in >> __drm_atomic_helper_connector_reset. > > This commit message is nonsense; if > __drm_atomic_helper_connector_reset() would dereference the NULL implied > by &mw_state->base, it would equally still dereference the explicit NULL > pointer passed after this patch. > > The current code works out OK because "base" is the first member of > struct malidp_mw_connector_state, thus if mw_state is NULL then > &mw_state->base == NULL + 0 == NULL. Now you *could* argue that this > isn't robust if the layout of struct malidp_mw_connector_state ever > changes, and that could be a valid justification for making this change, > but the reason given certainly isn't. > > Arithmetic on a (potentially) NULL pointer may well be a sign that it's > worth a closer look to check whether it really is what the code intended > to do, but don't automatically assume it has to be a bug. Otherwise, > good luck with "fixing" every user of container_of() throughout the > entire kernel. I have sent a new patch with the modified commit mesage. Thanks, Jiang
