In the Linux kernel, the following vulnerability has been resolved:
perf/core: Allow list_del during perf_event_overflow()
A PMU might use perf_sched_cb_inc() and perf_sched_cb_dec()
interface to get the PMU call back function pmu::sched_task
invoked at schedule in and schedule out. This is achieved
by walking along the list anchored by sched_cb_list.
The following scenario might lead to a list corruption.
perf_pmu_sched_task()
for_each_list_entry(…, &sched_cb_list)
+–> __perf_pmu_sched_task()
+–> event->pmu->sched_task())
+–> PMU_push_sample()
+–> perf_event_overflow()
+–> __perf_event_overflow()
+–> pmu->stop()
+–> perf_sched_cb_dec()
remove entry from sched_cb_list
while list node in use.
This happens when ioctl(fd, PERF_EVENT_IOC_REFRESH, xxx) has been
invoked and perf_event::event_limit hits zero.
Prevent the list corruption and convert for_each_list_entry()
to for_each_list_entry_safe().
