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. v2: fix comment style and typo in the warning pointed out by Thomas Signed-off-by: Christian König <christian.koenig@xxxxxxx> Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> --- drivers/dma-buf/dma-fence-array.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c index 3e07f961e2f3..cb1bacb5a42b 100644 --- a/drivers/dma-buf/dma-fence-array.c +++ b/drivers/dma-buf/dma-fence-array.c @@ -176,6 +176,20 @@ 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 (num_fences--) + WARN_ON(dma_fence_is_container(fences[num_fences])); + return array; } EXPORT_SYMBOL(dma_fence_array_create); -- 2.25.1
