On Thu, Mar 13, 2025 at 11:09:44AM +0100, Luca Ceresoli wrote:
> Hello Anusha,
>
> On Wed, 12 Mar 2025 20:54:42 -0400
> Anusha Srivatsa <asrivats@xxxxxxxxxx> wrote:
>
> > Introduce reference counted allocations for panels to avoid
> > use-after-free. The patch adds the macro devm_drm_bridge_alloc()
> > to allocate a new refcounted panel. Followed the documentation for
> > drmm_encoder_alloc() and devm_drm_dev_alloc and other similar
> > implementations for this purpose.
> >
> > Also adding drm_panel_get() and drm_panel_put() to suitably
> > increment and decrement the refcount
> >
> > Signed-off-by: Anusha Srivatsa <asrivats@xxxxxxxxxx>
>
> I'm very happy to see the very first step of the panel rework mentioned
> by Maxime see the light! :-)
>
> This patch looks mostly good to me, and the similarity with my bridge
> refcounting work is by itself reassuring.
>
> I have a few notes, one is relevant and the others are minor details,
> see below.
>
> In the Subject line: s/allocatons/allocations/
>
> [...]
>
> > +void *__devm_drm_panel_alloc(struct device *dev, size_t size, size_t offset,
> > + const struct drm_panel_funcs *funcs)
> > +{
> > + void *container;
> > + struct drm_panel *panel;
> > + int err;
> > +
> > + if (!funcs) {
> > + dev_warn(dev, "Missing funcs pointer\n");
> > + return ERR_PTR(-EINVAL);
> > + }
> > +
> > + container = kzalloc(size, GFP_KERNEL);
> > + if (!container)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + panel = container + offset;
> > + panel->container_offset = offset;
> > + panel->funcs = funcs;
> > + kref_init(&panel->refcount);
> > +
> > + err = devm_add_action_or_reset(dev, drm_panel_put_void, panel);
> > + if (err)
> > + return ERR_PTR(err);
> > +
> > + drm_panel_init(panel, dev, funcs, panel->connector_type);
>
> panel->connector_type here is uninitialized. You are passing
> panel->connector_type to drm_panel_init(), which will then copy it into
> panel->connector_type itself.
Yeah, we need to have the connector type as a parameter.
Maxime
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