Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [High] Dynamically allocating `struct drm_driver` with `devm_kzalloc` creates a Use-After-Free on device unbind. --
--- Patch [4]: [PATCH v2 4/5] drm/nouveau/kms: Only allow enabling atomic modesetting on nv50+ --- commit 5c23d4459a380de49a6e089b9ca550a380ff5d97 Author: Lyude Paul <[email protected]> drm/nouveau/kms: Only allow enabling atomic modesetting on nv50+ Atomic modesetting support was never added for pre-nv50 chipsets, so make sure we don't allow it to be forced on. Additionally, print a small warning when it's not supported. > diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c > b/drivers/gpu/drm/nouveau/nouveau_drm.c > index ae489dc1b1943..33f60f5d4d9f3 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_drm.c > +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c > @@ -770,8 +770,12 @@ nouveau_drm_device_new(struct device *parent, struct > nvkm_device *device) > goto done; > } > > - if (nouveau_atomic) > - drm_driver->driver_features |= DRIVER_ATOMIC; > + if (nouveau_atomic) { > + if (drm->device.info.family >= NV_DEVICE_INFO_V0_TESLA) > + drm_driver->driver_features |= DRIVER_ATOMIC; [Severity: High] Earlier in nouveau_drm_device_new(), drm_driver is dynamically allocated with devm_kzalloc(): drm_driver = devm_kzalloc(parent, sizeof(*drm_driver), GFP_KERNEL); if (!drm_driver) return ERR_PTR(-ENOMEM); Can this create a use-after-free on device unbind? If userspace opens the DRM device node, it takes a reference on the drm_device object. If the PCI device is hot-unplugged or manually unbound, devres cleanup frees the drm_driver (along with nouveau_drm). Later, when userspace closes the DRM file descriptor, drm_release() calls drm_dev_needs_global_mutex() which evaluates dev->driver->driver_features, and eventually executes dev->driver->postclose(), dereferencing the freed memory. > + else > + NV_WARN(drm, "Atomic modesetting not supported (needs > nv50+)\n"); > + } > > ret = nvif_device_map(&drm->device); > if (ret) { -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=4
