linux/drivers/block/rbd.c
Ilya Dryomov 1e335cfce3 rbd: prevent kernel stack blow up on rbd map
commit 6d69bb536b upstream.

Mapping an image with a long parent chain (e.g. image foo, whose parent
is bar, whose parent is baz, etc) currently leads to a kernel stack
overflow, due to the following recursion in the reply path:

  rbd_osd_req_callback()
    rbd_obj_request_complete()
      rbd_img_obj_callback()
        rbd_img_parent_read_callback()
          rbd_obj_request_complete()
            ...

Limit the parent chain to 16 images, which is ~5K worth of stack.  When
the above recursion is eliminated, this limit can be lifted.

Fixes: http://tracker.ceph.com/issues/12538

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Josh Durgin <jdurgin@redhat.com>
[idryomov@gmail.com: backport to 4.1: rbd_dev->opts]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-11-09 14:33:36 -08:00

5774 lines
146 KiB