CVE-2026-98552perf/core: Fix a refcount leak in attach_perf_ctx_data()

Official description

In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix a refcount leak in attach_perf_ctx_data() The attach_perf_ctx_data() can race on global and !global cases. The global case is protected by global_ctx_data_rwsem and shares a single reference count using perf_ctx_data.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 ---------------------------------------------------------------- attach_task_ctx_data(.global=1) attach_task_ctx_data(.global=0) cd1 = alloc_perf_ctx_data(); cd2 = alloc_perf_ctx_data(); // { .global = 0, .refcount = 1 }; try_cmpxchg(); // success, // task->perf_ctx_data = cd2 try_cmpxhg(); // fail; old = cd2 refcount_inc_not_zero(&old->refcount); // success // old.refcount = 2 free_perf_ctx_data(cd1); Then later detach_global_ctx_data() will see the data but it's not marked as global, so it won't call detach_task_ctx_data().

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/23250517cd475367653f1e99396967f54c6f1b7c
• https://git.kernel.org/stable/c/5286d4eb5cd7e10d7d93c3cc596e18bc8ad80f72
• https://git.kernel.org/stable/c/cca4980630b3c7a85f53cb43c6018184ce5d4e37