In the Linux kernel, the following vulnerability has been resolved:s390/cpum_sf: Fix and protect memory allocation of SDBs with mutexReservation of the PMU hardware is done at first event creationand is protected by a pair of mutex_lock() and mutex_unlock().After reservation of the PMU hardware the memoryrequired for the PMUs the event is to be installed on isallocated by allocate_buffers() and alloc_sampling_buffer().This done outside of the mutex protection.Without mutex protection two or more concurrent invocations ofperf_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 bymutex.
