Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
New issues: - [Low] Imported dma-buf objects are incorrectly placed into the unbacked LRU list instead of the pinned LRU list. Pre-existing issues: - [Critical] Failure path in `msm_gem_import` incorrectly treats the imported object as a native object, erroneously freeing the exporter's `sg_table` and dropping page references, leading to a NULL pointer dereference. -- --- Patch [10]: [PATCH v6 10/16] drm/msm/gem: Extract bookkeeping init helper --- commit e9867494af3de09952793735c8d5be5dc88c19a0 Author: Rob Clark <[email protected]> drm/msm/gem: Extract bookkeeping init helper Clean up duplicated logic between import and new paths. > diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c > index a358fb5ca6d73..961e22d3c7292 100644 > --- a/drivers/gpu/drm/msm/msm_gem.c > +++ b/drivers/gpu/drm/msm/msm_gem.c > @@ -1233,10 +1233,21 @@ static int msm_gem_new_impl(struct drm_device *dev, > uint32_t flags, > return 0; > } > > +static int msm_gem_init_bookkeeping(struct drm_gem_object *obj) > +{ > + struct msm_drm_private *priv = obj->dev->dev_private; > + > + drm_gem_lru_move_tail(&priv->lru.unbacked, obj); [Severity: Low] Does this hardcode the unbacked LRU list for all callers? The previous code for imported objects placed them in the pinned LRU. Will this now route an imported, page-backed object into the unbacked LRU? > + > + mutex_lock(&priv->obj_lock); > + list_add_tail(&to_msm_bo(obj)->node, &priv->objects); > + mutex_unlock(&priv->obj_lock); > + > + return drm_gem_create_mmap_offset(obj); > +} [ ... ] > @@ -1314,13 +1316,7 @@ struct drm_gem_object *msm_gem_import(struct > drm_device *dev, > goto fail; > } > > - drm_gem_lru_move_tail(&priv->lru.pinned, obj); > - > - mutex_lock(&priv->obj_lock); > - list_add_tail(&msm_obj->node, &priv->objects); > - mutex_unlock(&priv->obj_lock); > - > - ret = drm_gem_create_mmap_offset(obj); > + ret = msm_gem_init_bookkeeping(obj); > if (ret) > goto fail; [Severity: Critical] This is a pre-existing issue, but can this failure path lead to a NULL pointer dereference and double-free? If msm_gem_init_bookkeeping() fails (e.g. from -ENOSPC) and we take this goto fail path, drm_gem_object_put(obj) will be called. Because import_attach is still NULL at this point, msm_gem_free_object() will see drm_gem_is_imported(obj) as false and treat it as a native object: drivers/gpu/drm/msm/msm_gem.c:msm_gem_free_object() { if (drm_gem_is_imported(obj)) { ... } else { msm_gem_vunmap(obj); put_pages(obj); } } This would free the exporter's sgt using sg_free_table() and kfree(). It would also call drm_gem_put_pages() which unconditionally dereferences obj->filp: drivers/gpu/drm/drm_gem.c:drm_gem_put_pages() { mapping = file_inode(obj->filp)->i_mapping; ... } Since this object was initialized with drm_gem_private_object_init(), obj->filp is NULL, causing a panic. -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=10
