When hardware or firmware initialization fails, the graphics engine (gr) or device functions may remain NULL. Attempting to access these during the GETPARAM ioctl (e.g., NOUVEAU_GETPARAM_GRAPH_UNITS) results in a kernel NULL pointer dereference, causing a crash when userspace (GNOME/Mesa) attempts to probe the device.
Add safety checks for 'gr', 'gr->func', and 'nvkm_device->func' in the ioctl handler. Return -ENODEV to signal the missing hardware state to userspace, and use NV_ERROR_ONCE to provide diagnostic proof in the kernel log without risking a console flood. RFC: These crashes may not be repeatable, they happened while I was trying to build nouveau as a builtin module, with binary blobs in the kernel image, on a laptop with an encrypted disk. Gemini tells me this won't work, so I punted. Signed-off-by: Jim Cromie <[email protected]> --- drivers/gpu/drm/nouveau/nouveau_abi16.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_abi16.c b/drivers/gpu/drm/nouveau/nouveau_abi16.c index 291203121f0c..c9270c5b0fac 100644 --- a/drivers/gpu/drm/nouveau/nouveau_abi16.c +++ b/drivers/gpu/drm/nouveau/nouveau_abi16.c @@ -306,7 +306,12 @@ nouveau_abi16_ioctl_getparam(ABI16_IOCTL_ARGS) getparam->value = 1; break; case NOUVEAU_GETPARAM_GRAPH_UNITS: - getparam->value = nvkm_gr_units(gr); + if (gr && gr->func) { + getparam->value = nvkm_gr_units(gr); + } else { + NV_ERROR_ONCE(drm, "GETPARAM_GRAPH_UNITS: no gr engine or func\n"); + return -ENODEV; + } break; case NOUVEAU_GETPARAM_EXEC_PUSH_MAX: { int ib_max = getparam_dma_ib_max(device); @@ -315,11 +320,23 @@ nouveau_abi16_ioctl_getparam(ABI16_IOCTL_ARGS) break; } case NOUVEAU_GETPARAM_VRAM_BAR_SIZE: - getparam->value = nvkm_device->func->resource_size(nvkm_device, NVKM_BAR1_FB); + if (nvkm_device && nvkm_device->func && nvkm_device->func->resource_size) { + getparam->value = + nvkm_device->func->resource_size(nvkm_device, NVKM_BAR1_FB); + } else { + NV_ERROR_ONCE(drm, "GETPARAM_VRAM_BAR_SIZE: no device func\n"); + return -ENODEV; + } break; case NOUVEAU_GETPARAM_VRAM_USED: { - struct ttm_resource_manager *vram_mgr = ttm_manager_type(&drm->ttm.bdev, TTM_PL_VRAM); - getparam->value = (u64)ttm_resource_manager_usage(vram_mgr); + struct ttm_resource_manager *vram_mgr = + ttm_manager_type(&drm->ttm.bdev, TTM_PL_VRAM); + if (vram_mgr) { + getparam->value = (u64)ttm_resource_manager_usage(vram_mgr); + } else { + NV_ERROR_ONCE(drm, "GETPARAM_VRAM_USED: no vram mgr\n"); + return -ENODEV; + } break; } case NOUVEAU_GETPARAM_HAS_VMA_TILEMODE: -- 2.55.0
