Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
New issues: - [Medium] Incorrect error check `WARN_ON(!panel->bridge)` masks bridge allocation failures, leading to invalid state. Pre-existing issues: - [High] Architectural Use-After-Free on panel memory when the panel unbinds. -- --- Patch [5]: [PATCH 05/11] drm/bridge: panel: add a panel_bridge to every panel --- commit fe7eeb215d441faca3cc4f0f4f95d9a96a4fb587 Author: Luca Ceresoli <[email protected]> drm/bridge: panel: add a panel_bridge to every panel Adding a panel does currently not add a panel_bridge wrapping it. Usually the panel_bridge creation happens later, when some other driver (e.g. the previous bridge or the encoder) calls *_of_get_bridge() and the following element in the pipeline is a panel. [ ... ] Switch to the new approach: always create a panel_bridge with a drm_panel, thus matching the lifetime of the drm_panel and the panel_bridge wrapping it. This makes lifetime much more straightforward to understand and to further develop on. [Severity: High] This is a pre-existing issue, but does the underlying bridge allocation architecture have a use-after-free risk when panels unbind? Looking at drm_panel_bridge_add_typed() in drivers/gpu/drm/bridge/panel.c: struct drm_bridge *drm_panel_bridge_add_typed(...) { ... panel_bridge = devm_drm_bridge_alloc(panel->dev, struct panel_bridge, bridge, &panel_bridge_bridge_funcs); ... } Since devres automatically frees the bridge memory when the panel unbinds (e.g., via rmmod), this completely ignores the bridge->refcount kref. For child-parent topologies like DSI panels where fw_devlink cannot enforce unbind ordering, couldn't the DSI host remain bound and retain a dangling pointer to the freed bridge in its chain? [ ... ] > diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c > index f8f6082e637fd..95fc95d1b4b7a 100644 > --- a/drivers/gpu/drm/drm_panel.c > +++ b/drivers/gpu/drm/drm_panel.c > @@ -453,6 +453,9 @@ void *__devm_drm_panel_alloc(struct device *dev, size_t > size, size_t offset, > > drm_panel_init(panel, dev, funcs, connector_type); > > + panel->bridge = devm_drm_panel_bridge_add(dev, panel); > + WARN_ON(!panel->bridge); [Severity: Medium] Will this check actually catch failures? devm_drm_panel_bridge_add() returns an ERR_PTR on failure, rather than NULL. If the allocation fails due to memory pressure or an invalid connector type, the warning will be silently bypassed since an ERR_PTR evaluates to true. The panel driver will then complete allocation successfully but with an error pointer in panel->bridge, which can cause display controllers to defer probing indefinitely without any error logs. Should this use IS_ERR() instead of checking for NULL? > + > return container; > } > EXPORT_SYMBOL(__devm_drm_panel_alloc); -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=5
