cpufreq: powernv: Fix use-after-free
commit d0a72efa upstream. The cpufreq driver has a use-after-free that we can hit if: a) There's an OCC message pending when the notifier is registered, and b) The cpufreq driver fails to register with the core. When a) occurs the notifier schedules a workqueue item to handle the message. The backing work_struct is located on chips[].throttle and when b) happens we clean up by freeing the array. Once we get to the (now free) queued item and the kernel crashes. Fixes: c5e29ea7 ("cpufreq: powernv: Fix bugs in powernv_cpufreq_{init/exit}") Cc: stable@vger.kernel.org # v4.6+ Signed-off-by:Oliver O'Halloran <oohall@gmail.com> Reviewed-by:
Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200206062622.28235-1-oohall@gmail.com Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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