Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
New issues: - [High] Embedding the `drm_driver` struct inside the dynamically allocated `nouveau_drm` struct causes a Use-After-Free when the device is unplugged but userspace holds open DRM file descriptors. Pre-existing issues: - [Critical] nouveau_drm_device_new() incorrectly returns 0 (NULL) on success, causing an immediate kernel panic during device probe. -- --- Patch [3]: [PATCH v3 3/5] drm/nouveau: Fix drm_driver struct/nouveau.atomic parameter handling --- commit d192ca1eced4bd2c1c15cea6e0c5ae59ed261add Author: Lyude Paul <[email protected]> drm/nouveau: Fix drm_driver struct/nouveau.atomic parameter handling The way we handled the nouveau.atomic module parameter before was fairly broken, and had a number of issues: [ ... ] > diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c > b/drivers/gpu/drm/nouveau/nouveau_drm.c > index 6940e774ace07..95daf2643e1df 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_drm.c > +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c [ ... ] > @@ -727,8 +725,7 @@ nouveau_drm_device_del(struct nouveau_drm *drm) > } > > static struct nouveau_drm * > -nouveau_drm_device_new(const struct drm_driver *drm_driver, struct device > *parent, > - struct nvkm_device *device) > +nouveau_drm_device_new(struct device *parent, struct nvkm_device *device) > { [Severity: Critical] This is a pre-existing issue (introduced earlier in the series), but does nouveau_drm_device_new() incorrectly return 0 (NULL) on success? At the end of nouveau_drm_device_new(), it returns 0: return 0; err_free_drm: This causes callers like nouveau_drm_probe() to incorrectly bypass the IS_ERR() check, as IS_ERR(NULL) is false: nouveau_drm_probe() drm = nouveau_drm_device_new(&pdev->dev, device); if (IS_ERR(drm)) { ret = PTR_ERR(drm); goto fail_nvkm; } ret = pci_enable_device(pdev); if (ret) goto fail_drm; ret = nouveau_drm_device_init(drm); The NULL pointer is then passed to nouveau_drm_device_init(), which immediately dereferences it and causes a kernel panic during device probe. [ ... ] > diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h > b/drivers/gpu/drm/nouveau/nouveau_drv.h > index 5fc75dc750ed0..5cc0001134e74 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_drv.h > +++ b/drivers/gpu/drm/nouveau/nouveau_drv.h > @@ -216,6 +216,7 @@ struct nouveau_drm { > > struct nouveau_cli client; > struct drm_device *dev; > + struct drm_driver drm_driver; [Severity: High] Can embedding the drm_driver struct inside the dynamically allocated nouveau_drm struct cause a use-after-free when the device is unplugged? When the device is unbound, nouveau_drm_device_del() drops the driver's reference to the DRM device and then immediately frees the nouveau_drm struct using kfree(): drivers/gpu/drm/nouveau/nouveau_drm.c:nouveau_drm_device_del() { if (drm->dev) drm_dev_put(drm->dev); ... kfree(drm); } Because drm_driver is now embedded in nouveau_drm, the drm_driver struct is also freed here. If userspace still has an open file descriptor, the drm_device remains alive. When userspace later closes the file descriptor, DRM core functions (such as drm_release) will attempt to dereference dev->driver (e.g., dev->driver->postclose), resulting in a use-after-free. > > struct list_head clients; > -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=3
