| From db3ee748eeee2324029d80f9bd85fe5798f52637 Mon Sep 17 00:00:00 2001 |
| From: Oliver O'Halloran <oohall@gmail.com> |
| Date: Thu, 6 Feb 2020 17:26:21 +1100 |
| Subject: [PATCH] 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 <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: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c |
| index 56f4bc0d209e..1806b1da4366 100644 |
| --- a/drivers/cpufreq/powernv-cpufreq.c |
| +++ b/drivers/cpufreq/powernv-cpufreq.c |
| @@ -1080,6 +1080,12 @@ 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); |
| } |
| |
| -- |
| 2.7.4 |
| |
