From: Jim Cromie <[email protected]> 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. NOTE: I encountered these crashes while booting unrelated code (in dynamic-debug) on real HW. There was also some fwupd updates around this time, so it could all be transient/unreproducible. But it did happen, and could happen again in unforseen circumstances. @Capitain_Jack tested the error path in v1 by deleting the FW Signed-off-by: Jim Cromie <[email protected]> Tested-by: Daniel Campos Ramos <[email protected]> --- drivers/gpu/drm/nouveau/nouveau_abi16.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_abi16.c b/drivers/gpu/drm/nouveau/nouveau_abi16.c index 4542d5f4ded8..3f130cd4fbcd 100644 --- a/drivers/gpu/drm/nouveau/nouveau_abi16.c +++ b/drivers/gpu/drm/nouveau/nouveau_abi16.c @@ -306,6 +306,11 @@ nouveau_abi16_ioctl_getparam(ABI16_IOCTL_ARGS) getparam->value = 1; break; case NOUVEAU_GETPARAM_GRAPH_UNITS: + if (!gr || !gr->func) { + NV_ERROR_ONCE(drm, "GETPARAM_GRAPH_UNITS: no gr engine or func\n"); + return -ENODEV; + } + getparam->value = nvkm_gr_units(gr); break; case NOUVEAU_GETPARAM_EXEC_PUSH_MAX: { @@ -315,10 +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) { + NV_ERROR_ONCE(drm, "GETPARAM_VRAM_BAR_SIZE: no device func\n"); + return -ENODEV; + } + + getparam->value = + nvkm_device->func->resource_size(nvkm_device, NVKM_BAR1_FB); break; case NOUVEAU_GETPARAM_VRAM_USED: { - struct ttm_resource_manager *vram_mgr = ttm_manager_type(&drm->ttm.bdev, TTM_PL_VRAM); + struct ttm_resource_manager *vram_mgr = + ttm_manager_type(&drm->ttm.bdev, TTM_PL_VRAM); + + if (!vram_mgr) { + NV_ERROR_ONCE(drm, "GETPARAM_VRAM_USED: no vram mgr\n"); + return -ENODEV; + } + getparam->value = (u64)ttm_resource_manager_usage(vram_mgr); break; } -- 2.56.0
