From 88a8e3c5a4c6bd353dc69b48f4a9d9331d19299d Mon Sep 17 00:00:00 2001 From: Oliver O'Halloran Date: Thu, 6 Feb 2020 17:26:21 +1100 Subject: cpufreq: powernv: Fix use-after-free commit d0a72efac89d1c35ac55197895201b7b94c5e6ef 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: c5e29ea7ac14 ("cpufreq: powernv: Fix bugs in powernv_cpufreq_{init/exit}") Cc: stable@vger.kernel.org # v4.6+ Signed-off-by: Oliver O'Halloran Reviewed-by: Gautham R. Shenoy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200206062622.28235-1-oohall@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/cpufreq/powernv-cpufreq.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'drivers/cpufreq') diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c index a1d7fa48229d..b4fc65512aad 100644 --- a/drivers/cpufreq/powernv-cpufreq.c +++ b/drivers/cpufreq/powernv-cpufreq.c @@ -955,6 +955,12 @@ static int init_chip_info(void) static inline void clean_chip_info(void) { + int i; + + /* flush any pending work items */ + if (chips) + for (i = 0; i < nr_chips; i++) + cancel_work_sync(&chips[i].throttle); kfree(chips); } -- cgit v1.2.3