On Wed, Sep 06, 2017 at 04:53:06PM -0700, Eric Biggers wrote:
From: Eric Biggers ebiggers@google.com
IDR only supports non-negative IDs. There used to be a 'WARN_ON_ONCE(id < 0)' in idr_replace(), but it was intentionally removed by commit 2e1c9b286765 ("idr: remove WARN_ON_ONCE() on negative IDs"). Then it was added back by commit 0a835c4f090a ("Reimplement IDR and IDA using the radix tree"). However it seems that adding it back was a mistake, given that some users such as drm_gem_handle_delete() (DRM_IOCTL_GEM_CLOSE) pass in a value from userspace to idr_replace(), allowing the WARN_ON_ONCE to be triggered. drm_gem_handle_delete() actually just wants idr_replace() to return an error code if the ID is not allocated, including in the case where the ID is invalid (negative).
Acked-by: Tejun Heo tj@kernel.org
Thanks.