On 1/20/22 14:27, 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>
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
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
Nit: First comment line of multi-line comments shouldn't contain text.
+ * 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]));
+
s/seqno/num_fences/g ?
Thanks,
Thomas
return array;
}
EXPORT_SYMBOL(dma_fence_array_create);
