linux-kernel - [PATCH 0/2] fix DT overlays when device links are released

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date: Fri, 02 Feb 2024 13:18:15 +0100
From: Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@...nel.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, 
 Frank Rowand <frowand.list@...il.com>, Rob Herring <robh+dt@...nel.org>, 
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
 Daniel Scally <djrscally@...il.com>, 
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
 Sakari Ailus <sakari.ailus@...ux.intel.com>, Len Brown <lenb@...nel.org>
Cc: linux-acpi@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org
Subject: [PATCH 0/2] fix DT overlays when device links are released

Link to RFC:
 * https://lore.kernel.org/lkml/20240123-fix-device-links-overlays-v1-1-9e4f6acaab6c@analog.com/

Changes since RFC:
 * Use a dedicated workqueue to remove devlinks;
 * Flush the devlink workqueue before checking the of_node refcount
   value.

The following series is the result of the discussion I had with Rafael.
To sum up the fundamental issue, device links drop their refcounts
asynchronously and that means that the of_node refcount associated with
the device will also be dropped asynchronously. Now, in
__of_changeset_entry_destroy(), the assumption is that the node refcount
must be 1 and that cannot be guaranteed given the above.

I'm pasting again the link of the first time I exposed the issue where
one can see the resulps (big splat) of failing DT assumption:

https://lore.kernel.org/linux-devicetree/20230511151047.1779841-1-nuno.sa@analog.com/

---
Nuno Sa (2):
      driver: core: add dedicated workqueue for devlink removal
      of: dynamic: flush devlinks workqueue before destroying the changeset

 drivers/base/core.c    | 33 +++++++++++++++++++++++++++++----
 drivers/of/dynamic.c   |  8 ++++++++
 include/linux/fwnode.h |  1 +
 3 files changed, 38 insertions(+), 4 deletions(-)
---
base-commit: 6613476e225e090cc9aad49be7fa504e290dd33d
change-id: 20240123-fix-device-links-overlays-5422e033a09b
--

Thanks!
- Nuno Sá