CVE-2026-64556

In the Linux kernel, the following vulnerability has been resolved:

perf/core: Detach event groups during remove_on_exec

perf_event_remove_on_exec() removes events by calling perf_event_exit_event(). For top-level events, this removes the event from the context with DETACH_EXIT only.

This can leave inconsistent group state when a removed event is a group leader and the group contains siblings without remove_on_exec. If the group was active, the surviving siblings can remain active and attached to the removed leaders sibling list, but are no longer represented by a valid group leader on the PMU context active lists.

A later close of the removed leader uses DETACH_GROUP and can promote the still-active siblings from this stale group state. The next schedule-in can then add an already-linked active_list entry again, corrupting the PMU context active list.

With DEBUG_LIST enabled, this is caught as a list_add double-add in merge_sched_in().

Fix this by detaching group relationships when remove_on_exec removes an event. This preserves the existing task-exit and revoke behavior, while ensuring surviving siblings are ungrouped before the removed event leaves the context.

Affected Software

References

• https://git.kernel.org/stable/c/037a3c43edfb597665dd34457cd22b14692f2ba3
• https://git.kernel.org/stable/c/06ccef0434e98058ddae7bcebc901f93d22b7653
• https://git.kernel.org/stable/c/39358e856fb89e62e3c8d7389a2dc4ec33dbe90e
• https://git.kernel.org/stable/c/4cdb1b3ab96eb1b7eb70bc5c82fede334bd60df2
• https://git.kernel.org/stable/c/a2d5d3ee7b6e3953114726b1521e62123ab5b043