Re: [PATCH v5 00/18] of: overlay: validation checks, subsequent fixes

[Alan Tull <atull@kernel.org>]

On Thu, Oct 18, 2018 at 5:48 PM <frowand.list@gmail.com> wrote:
>
> From: Frank Rowand <frank.rowand@sony.com>
>
> Add checks to (1) overlay apply process and (2) memory freeing
> triggered by overlay release.  The checks are intended to detect
> possible memory leaks and invalid overlays.

I've tested v5, nothing new to report.

Alan

>
> The checks revealed bugs in existing code.  Fixed the bugs.
>
> While fixing bugs, noted other issues, which are fixed in
> separate patches.
>
> *****  Powerpc folks: I was not able to test the patches that
> *****  directly impact Powerpc systems that use dynamic
> *****  devicetree.  Please review that code carefully and
> *****  test.  The specific patches are: 03/16, 04/16, 07/16
>
> FPGA folks:
>
>   I made the validation checks that should result in an
>   invalid live devicetree report "ERROR" and cause the overlay apply
>   to fail.
>
>   I made the memory leak validation tests report "WARNING" and allow
>   the overlay apply to complete successfully.  Please let me know
>   if you encounter the warnings.  There are at least two paths
>   forward to deal with the cases that trigger the warning: (1) change
>   the warning to an error and fail the overlay apply, or (2) find a
>   way to detect the potential memory leaks and free the memory
>   appropriately.
>
> ALL people:
>
>   The validations do _not_ address another major concern I have with
>   releasing overlays, which is use after free errors.
>
> Changes since v4:
>   - 01/18: make error message format consistent, error first, path last
>   - 09/18: create of_prop_val_eq() and change open code to use it
>   - 09/18: remove extra blank lines
>
> Changes since v3:
>   - 01/18: Add expected value of refcount for destroy cset entry error.  Also
>     explain the cause of the error.
>
>   - 09/18: for errors of an overlay changing the value of #size-cells or
>     #address-cells, return -EINVAL so that overlay apply will fail
>   - 09/18: for errors of an overlay changing the value of #size-cells or
>     #address-cells, make the message more direct.
>     Old message:
>       OF: overlay: ERROR: overlay and/or live tree #size-cells invalid in node /soc/base_fpga_region
>     New message:
>       OF: overlay: ERROR: changing value of /soc/base_fpga_region/#size-cells not allowed
>
>   - 13/18: Update patch comment header to state that this patch modifies the
>     previous patch to not return immediately on fragment error and
>     explain this is not a performance issue.
>   - 13/18: remove redundant "overlay" from two error messages.  "OF: overlay:"
>     is already present in pr_fmt()
>
> Changes since v2:
>
>   - 13/18: Use continue to reduce indentation in find_dup_cset_node_entry()
>     and find_dup_cset_prop()
>
> Changes since v1:
>
>   - move patch 16/16 to 17/18
>   - move patch 15/16 to 18/18
>   - new patch 15/18
>   - new patch 16/18
>
>   - 05/18: add_changeset_node() header comment: incorrect comment for @target
>
>   - 18/18: add same fix for of_parse_phandle_with_args()
>   - 18/18: add same fix for of_parse_phandle_with_args_map()
>
>
> *** BLURB HERE ***
>
> Frank Rowand (18):
>   of: overlay: add tests to validate kfrees from overlay removal
>   of: overlay: add missing of_node_put() after add new node to changeset
>   of: overlay: add missing of_node_get() in __of_attach_node_sysfs
>   powerpc/pseries: add of_node_put() in dlpar_detach_node()
>   of: overlay: use prop add changeset entry for property in new nodes
>   of: overlay: do not duplicate properties from overlay for new nodes
>   of: dynamic: change type of of_{at,de}tach_node() to void
>   of: overlay: reorder fields in struct fragment
>   of: overlay: validate overlay properties #address-cells and
>     #size-cells
>   of: overlay: make all pr_debug() and pr_err() messages unique
>   of: overlay: test case of two fragments adding same node
>   of: overlay: check prevents multiple fragments add or delete same node
>   of: overlay: check prevents multiple fragments touching same property
>   of: unittest: remove unused of_unittest_apply_overlay() argument
>   of: overlay: set node fields from properties when add new overlay node
>   of: unittest: allow base devicetree to have symbol metadata
>   of: unittest: find overlays[] entry by name instead of index
>   of: unittest: initialize args before calling of_*parse_*()
>
>  arch/powerpc/platforms/pseries/dlpar.c             |  15 +-
>  arch/powerpc/platforms/pseries/reconfig.c          |   6 +-
>  drivers/of/dynamic.c                               |  68 +++--
>  drivers/of/kobj.c                                  |   4 +-
>  drivers/of/overlay.c                               | 292 ++++++++++++++++-----
>  drivers/of/unittest-data/Makefile                  |   2 +
>  .../of/unittest-data/overlay_bad_add_dup_node.dts  |  28 ++
>  .../of/unittest-data/overlay_bad_add_dup_prop.dts  |  24 ++
>  drivers/of/unittest-data/overlay_base.dts          |   1 +
>  drivers/of/unittest.c                              |  96 +++++--
>  include/linux/of.h                                 |  25 +-
>  11 files changed, 439 insertions(+), 122 deletions(-)
>  create mode 100644 drivers/of/unittest-data/overlay_bad_add_dup_node.dts
>  create mode 100644 drivers/of/unittest-data/overlay_bad_add_dup_prop.dts
>
> --
> Frank Rowand <frank.rowand@sony.com>
>