CVE-2024-56706

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

s390/cpum_sf: Fix and protect memory allocation of SDBs with mutex

Reservation of the PMU hardware is done at first event creation

and is protected by a pair of mutex_lock() and mutex_unlock().

After reservation of the PMU hardware the memory

required for the PMUs the event is to be installed on is

allocated by allocate_buffers() and alloc_sampling_buffer().

This done outside of the mutex protection.

Without mutex protection two or more concurrent invocations of

perf_event_init() may run in parallel.

This can lead to allocation of Sample Data Blocks (SDBs)

multiple times for the same PMU.

Prevent this and protect memory allocation of SDBs by

mutex.