tree d2a14f96f81667795bbafdd02e7ad4bd162412b9
parent b682c6d41bc23353b5d80e02ca4961ac67624f4c
author Xiubo Li <xiubli@redhat.com> 1593582768 -0400
committer Ilya Dryomov <idryomov@gmail.com> 1596445521 +0200

ceph: fix potential mdsc use-after-free crash

Make sure the delayed work stopped before releasing the resources.

cancel_delayed_work_sync() will only guarantee that the work finishes
executing if the work is already in the ->worklist.  That means after
the cancel_delayed_work_sync() returns, it will leave the work requeued
if it was rearmed at the end. That can lead to a use after free once the
work struct is freed.

Fix it by flushing the delayed work instead of trying to cancel it, and
ensure that the work doesn't rearm if the mdsc is stopping.

URL: https://tracker.ceph.com/issues/46293
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>