[RFC,v2,0/4] Dynamic OF and use after free related fixes

Message

Nuno Sa May 31, 2022, 12:45 p.m. UTC

This series is a collection of fixes with things I encountered when
handling a system with device tree overlays "fun". This effectively means
removing and adding devices which led to me the found issues.

patch 1 is fairly straight and indeed an issue related with of_nodes not
being put.

For patches 2 and 3, they are only triggered if someone first removes the
provider which is a dumb thing to do. However, I guess we should be
prepared for that and the framework even has some efforts to deal with
these cases (eg: clk_nodrv_ops). That said, patch 2 is more or less
straight (even though catching the guilty line wasn't), we add something
to a list during resgister, we need to remove it on the unregister path.
Patch 3 is a different beast... though I think krefs are the proper solution
here, I'm not sure I covered all the corner cases with all the reparenting
that might happen (mainly reason why this is RFC). Nullyfing
clk_core->parent during unregister might suffice but I'm more in favor of
proper refcounting (for now at least). Patch 3 also does not have a fixes
tag because I genuily don't know when this became a problem. Maybe right
from the beginning?

Patch 4 is just a minor improvement and not really a fix...

v2:
 * add an helper function in '__set_clk_parents()' to set each parent
separately;
 * massaged commit message in patch 2/4
("clk: fix clk not being unlinked from consumers list") as per Stephen
feedback.

Nuno Sá (4):
  clk: clk-conf: properly release of nodes
  clk: fix clk not being unlinked from consumers list
  clk: refcount the active parent clk_core
  clk: use clk_core_unlink_consumer() helper

 drivers/clk/clk-conf.c | 126 +++++++++++++++++++++++++----------------
 drivers/clk/clk.c      |  83 +++++++++++++++++----------
 2 files changed, 131 insertions(+), 78 deletions(-)