Re: [PATCH net] net: dsa: fix 'increment on 0' warning

From: Vivien Didelot <redacted>
Date: Fri, 24 Nov 2017 11:36:06 -0500

Setting the refcount to 0 when allocating a tree to match the number of
switch devices it holds may cause an 'increment on 0; use-after-free',
if CONFIG_REFCOUNT_FULL is enabled.

To fix this, do not decrement the refcount of a newly allocated tree,
increment it when an already allocated tree is found, and decrement it
after the probing of a switch, as done with the previous behavior.

At the same time, make dsa_tree_get and dsa_tree_put accept a NULL
argument to simplify callers, and return the tree after incrementation,
as most kref users like of_node_get and of_node_put do.

Fixes: 8e5bf9759a06 ("net: dsa: simplify tree reference counting")
Signed-off-by: Vivien Didelot <redacted>

Applied, thanks Vivien.