Re: [PATCH v2 1/3] drm/nouveau/uvmm: fix NULL deref unwinding an OP_MAP_SPARSE op

Reviewed-by: Lyude Paul <[email protected]>

On Tue, 2026-08-11 at 16:46 +0800, Zhenhao Wan wrote:
> Each bind_job_op is zeroed by kzalloc_obj() in
> bind_job_op_from_uop(),
> and the OP_MAP_SPARSE case in nouveau_uvmm_bind_job_submit() only
> creates
> a region, so op->ops stays NULL for a successfully processed sparse
> map.
> 
> If a later op in the same job fails, the reverse unwind loop revisits
> that
> op and calls drm_gpuva_ops_free(&uvmm->base, op->ops)
> unconditionally.
> drm_gpuva_ops_free() dereferences its argument right away
> (list_for_each_entry_safe on &ops->list), so a NULL op->ops oopses.
> The
> path is reachable by any render-node fd holder, since NOUVEAU_VM_BIND
> is
> DRM_RENDER_ALLOW.
> 
> Guard the free with IS_ERR_OR_NULL(), as
> nouveau_uvmm_bind_job_cleanup()
> already does for the identical free.
> 
> Fixes: b88baab82871 ("drm/nouveau: implement new VM_BIND uAPI")
> Reported-by: Yuhao Jiang <[email protected]>
> Assisted-by: Claude:claude-opus-5
> Cc: [email protected]
> Signed-off-by: Zhenhao Wan <[email protected]>
> ---
>  drivers/gpu/drm/nouveau/nouveau_uvmm.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> index 36445915aa58..849bf42c124e 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> @@ -1489,7 +1489,8 @@ nouveau_uvmm_bind_job_submit(struct nouveau_job
> *job,
>  			break;
>  		}
>  
> -		drm_gpuva_ops_free(&uvmm->base, op->ops);
> +		if (!IS_ERR_OR_NULL(op->ops))
> +			drm_gpuva_ops_free(&uvmm->base, op->ops);
>  		op->ops = NULL;
>  		op->reg = NULL;
>  	}