cpufreq: powernv: Fix use-after-free
commitd0a72efac8
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:c5e29ea7ac
("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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@ -1080,6 +1080,12 @@ free_and_return:
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static inline void clean_chip_info(void)
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{
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int i;
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/* flush any pending work items */
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if (chips)
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for (i = 0; i < nr_chips; i++)
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cancel_work_sync(&chips[i].throttle);
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kfree(chips);
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}
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