Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [Medium] drm/atomic: non-idempotent list_del() in drm_atomic_private_obj_fini() --
commit 72c7eb0713fd45624f9e5b2b360640bc1c381470 Author: Maxime Ripard <[email protected]> drm/atomic: Fix private obj error handling This commit fixes drm_atomic_private_obj_init() to remove the object from privobj_list and clean up the modeset lock if atomic_create_state() fails. It also adds a list_empty() check to drm_atomic_private_obj_fini() to avoid a double list_del() when teardown runs after a failed initialization. > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c > index 9bb761eda59f4..8f9b17395b905 100644 > --- a/drivers/gpu/drm/drm_atomic.c > +++ b/drivers/gpu/drm/drm_atomic.c [ ... ] > @@ -1056,6 +1072,15 @@ EXPORT_SYMBOL(drm_atomic_private_obj_init); > void > drm_atomic_private_obj_fini(struct drm_private_obj *obj) > { > + /* > + * Some callers ignore drm_atomic_private_obj_init() failures > + * and unconditionally register a teardown action that calls > + * this function. Make it idempotent so a failed init followed > + * by fini does not cause a double list_del. > + */ > + if (list_empty(&obj->head)) > + return; > + > list_del(&obj->head); [Severity: Medium] Should drm_atomic_private_obj_fini() in drivers/gpu/drm/drm_atomic.c use list_del_init(&obj->head) instead of list_del(&obj->head) so that calling drm_atomic_private_obj_fini() more than once is truly idempotent? Because list_del(&obj->head) poisons obj->head.next with LIST_POISON1, a second call to drm_atomic_private_obj_fini() after a successful drm_atomic_private_obj_init() will see list_empty(&obj->head) evaluate to false. It will then execute list_del(&obj->head) on the poisoned list node and call obj->funcs->atomic_destroy_state(obj, obj->state) a second time on already-freed state (as well as kfree(obj->name) in the subsequent commit adding drm_private_obj names). In drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c, this happens when dpu_kms_hw_init() succeeds in dpu_kms_global_obj_init() -> drm_atomic_private_obj_init() and then fails at a later initialization step: dpu_kms_hw_init() error: _dpu_kms_hw_destroy(dpu_kms) dpu_kms_global_obj_fini(dpu_kms) drm_atomic_private_obj_fini(&dpu_kms->global_state) When the error propagates back to msm_drm_init() in drivers/gpu/drm/msm/msm_drv.c, teardown calls _dpu_kms_hw_destroy() a second time: msm_drm_init() msm_drm_uninit() msm_drm_kms_uninit() dpu_kms_destroy() _dpu_kms_hw_destroy(dpu_kms) dpu_kms_global_obj_fini(dpu_kms) drm_atomic_private_obj_fini(&dpu_kms->global_state) -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=4
