linux-kernel - Re: [PATCH v3 00/18] of: overlay: validation checks, subsequent fixes

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Message-ID: <CANk1AXTmY7v03m7NNZHVtzyU1Mwm0GYtOJQzmObFLASs=PEfLA@mail.gmail.com>
Date:   Mon, 15 Oct 2018 14:21:39 -0500
From:   Alan Tull <atull@...nel.org>
To:     Frank Rowand <frowand.list@...il.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Moritz Fischer <mdf@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, linux-fpga@...r.kernel.org
Subject: Re: [PATCH v3 00/18] of: overlay: validation checks, subsequent fixes

On Sun, Oct 14, 2018 at 7:26 PM <frowand.list@...il.com> wrote:
>
> From: Frank Rowand <frank.rowand@...y.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.
>
> 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.

I reran my FPGA testing.  The strings are fixed, no longer NULL.  I
have functionality back, my test passes now.  I'm seeing the intended
warnings about any properties added to existing nodes.  That includes
warnings about added symbols.  Below is a simplified part to show some
of what I'm seeing.

By the way my testing is all using Pantelis' DT overlay configfs interface.

root@...ia10:~# ./apply-static-region.sh

Applying dtbo: socfpga_arria10_socdk_sdmmc_ghrd_ovl_ext_cfg.dtb

[ 1821.088640] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/soc/base_fpga_region/ranges
[ 1821.103307] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/soc/base_fpga_region/external-fpga-config
[ 1821.117359] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/soc/base_fpga_region/clocks
[ 1821.130130] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/soc/base_fpga_region/clock-names
[ 1821.143449] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property: /__symbols__/clk_0
[ 1821.155357] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property: /__symbols__/ILC
[ 1821.167074] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/__symbols__/freeze_controller_0
[ 1821.180171] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/__symbols__/sysid_qsys_0
[ 1821.192662] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property: /__symbols__/led_pio
[ 1821.204720] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property: /__symbols__/button_pio
[ 1821.217034] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property: /__symbols__/dipsw_pio
[ 1821.231977] of-fpga-region soc:base_fpga_region:fpga_pr_region0:
FPGA Region probed
[ 1821.240144] altera_freeze_br ff200450.freeze_controller: fpga
bridge [freeze] registered

root@...ia10:~# ./apply-static-region.sh root@...ia10:~# rmdir
/sys/kernel/config/device-tree/overlays/1-socfpga_arria10_socdk_sdmmc_ghrd_ovl_ext_cfg.dtb

[ 1823.805564] OF: ERROR: memory leak - destroy cset entry: attach
overlay node /soc/base_fpga_region/clk_0 with refcount 2

Alan


Alan



>
> ALL people:
>
>   The validations do _not_ address another major concern I have with
>   releasing overlays, which is use after free errors.
>
> 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()
>
> 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                               | 298 ++++++++++++++++-----
>  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                                 |  19 +-
>  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@...y.com>
>