UBUNTU-CVE-2026-98552: Medium severity ubuntu/linux-hwe-edge vulnerability

In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix a refcount leak in attachperfctxdata() The attachperfctxdata() can race on global and !global cases. The global case is protected by globalctxdatarwsem and shares a single reference count using perfctxdata.global field. But when it races with !global case, it may miss to set the global field and result in a reference count leak. CPU1 CPU2 ---------------------------------------------------------------- attachtaskctxdata(.global=1) attachtaskctxdata(.global=0) cd1 = allocperfctxdata(); cd2 = allocperfctxdata(); // { .global = 0, .refcount = 1 }; trycmpxchg(); // success, // task->perfctxdata = cd2 trycmpxhg(); // fail; old = cd2 refcountincnotzero(&old->refcount); // success // old.refcount = 2 freeperfctxdata(cd1); Then later detachglobalctxdata() will see the data but it's not marked as global, so it won't call detachtaskctxdata().