On Wed, Jan 19, 2022 at 02:43:37PM +0100, Christian König wrote: > It's not allowed to nest another dma_fence container into a dma_fence_array > or otherwise we can run into recursion. > > Warn about that when we create a dma_fence_array. > > Signed-off-by: Christian König <christian.koenig@xxxxxxx> > --- > drivers/dma-buf/dma-fence-array.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c > index 3e07f961e2f3..4bfbcb885bbc 100644 > --- a/drivers/dma-buf/dma-fence-array.c > +++ b/drivers/dma-buf/dma-fence-array.c > @@ -176,6 +176,19 @@ struct dma_fence_array *dma_fence_array_create(int num_fences, > > array->base.error = PENDING_ERROR; > > + /* dma_fence_array objects should never contain any other fence > + * containers or otherwise we run into recursion and potential kernel > + * stack overflow on operations on the dma_fence_array. > + * > + * The correct way of handling this is to flatten out the array by the > + * caller instead. > + * > + * Enforce this here by checking that we don't create a dma_fence_array > + * with any container inside. > + */ > + while (seqno--) > + WARN_ON(dma_fence_is_container(fences[seqno])); Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > + > return array; > } > EXPORT_SYMBOL(dma_fence_array_create); > -- > 2.25.1 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
