In the Linux kernel, the following vulnerability has been resolved:
OPP: Fix race between OPP addition and lookup
A race exists between dev_pm_opp_add_dynamic() and dev_pm_opp_find_freq_exact():
CPU0 (add) CPU1 (lookup)
_opp_add() mutex_lock() list_add(&new_opp->node, head) mutex_unlock() _opp_table_find_key() mutex_lock() dev_pm_opp_get(opp) kref_get() mutex_unlock() kref_init(&new_opp->kref) dev_pm_opp_put() kref_put_mutex()
The newly added OPP is inserted into the list before its kref is initialized. A concurrent lookup can find this OPP and increment its reference count while it is still uninitialized, leading to refcount corruption and a potential premature free.
Fix this by initializing ->kref and ->opp_table before making the OPP visible via list_add(). This ensures any concurrent lookup observes a fully initialized object.
[ Viresh: Updated commit log ]