net: dsa: fix 'increment on 0' warning
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: 8e5bf975 ("net: dsa: simplify tree reference counting") Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Tested-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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