In the Linux kernel, the following vulnerability has been resolved:
powerpc/perf: Fix ref-counting on the PMU 'vpa_pmu'
Commit 176cda0619b6 ("powerpc/perf: Add perf interface to expose vpa
counters") introduced 'vpa_pmu' to expose Book3s-HV nested APIv2 provided
L1<->L2 context switch latency counters to L1 user-space via
perf-events. However the newly introduced PMU named 'vpa_pmu' doesn't
assign ownership of the PMU to the module 'vpa_pmu'. Consequently the
module 'vpa_pmu' can be unloaded while one of the perf-events are still
active, which can lead to kernel oops and panic of the form below on a
Pseries-LPAR:
BUG: Kernel NULL pointer dereference on read at 0x00000058
CWE-476