In the Linux kernel, the following vulnerability has been resolved:

drivers/perf: hisi: use cpuhp_state_remove_instance_nocalls() for hisi_hns3_pmu uninit process

When tearing down a 'hisi_hns3' PMU, we mistakenly run the CPU hotplug
callbacks after the device has been unregistered, leading to fireworks
when we try to execute empty function callbacks within the driver:

  | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
  | CPU: 0 PID: 15 Comm: cpuhp/0 Tainted: G        W  O      5.12.0-rc4+ #1
  | Hardware name:  , BIOS KpxxxFPGA 1P B600 V143 04/22/2021
  | pstate: 80400009 (Nzcv daif +PAN -UAO -TCO BTYPE=--)
  | pc : perf_pmu_migrate_context+0x98/0x38c
  | lr : perf_pmu_migrate_context+0x94/0x38c
  |
  | Call trace:
  |  perf_pmu_migrate_context+0x98/0x38c
  |  hisi_hns3_pmu_offline_cpu+0x104/0x12c [hisi_hns3_pmu]

Use cpuhp_state_remove_instance_nocalls() instead of
cpuhp_state_remove_instance() so that the notifiers don't execute after
the PMU device has been unregistered.

[will: Rewrote commit message]

kernel.org https://git.kernel.org/stable/c/3f5827371763f2d9c70719c270055a81d030f3d0 [No types assigned]

kernel.org https://git.kernel.org/stable/c/4589403a343bb0c72a6faf5898386ff964d4e01a [No types assigned]

kernel.org https://git.kernel.org/stable/c/50b560783f7f71790bcf70e9e9855155fb0af8c1 [No types assigned]

kernel.org https://git.kernel.org/stable/c/d04ff5437a45f275db5530efb49b68d0ec851f6f [No types assigned]