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 mutexlock() and mutexunlock(). After reservation of the PMU hardware the memory required for the PMUs the event is to be installed on is allocated by allocatebuffers() and allocsamplingbuffer(). This done outside of the mutex protection. Without mutex protection two or more concurrent invocations of perfevent_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.