libxmp through 4.7.4 Stack Out-of-Bounds Read via P61A Depacker

libxmp through 4.7.4 contains an off-by-one stack out-of-bounds read vulnerability in the prowizard P61A depacker depack_p61a() in src/loaders/prowizard/p61a.c. Attackers can supply a crafted headerless P61A module with 31 samples and a 0xffe0 back-reference size word to leak stack memory into sample metadata or disrupt loading.