Bug 2508319 (CVE-2026-64556)

Summary: CVE-2026-64556 kernel: perf/core: Detach event groups during remove_on_exec
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's performance monitoring unit (PMU) subsystem. This vulnerability occurs when a performance event group leader is removed during process execution, but its associated events (siblings) remain active and linked to a stale list. This inconsistent state can lead to a corruption of the PMU context active list, potentially causing system instability or a denial of service. A local attacker could potentially exploit this to disrupt system operations.
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Description OSIDB Bzimport 2026-07-29 09:01:36 UTC 
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 leader's 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.
Comment 1 TEJ RATHI 2026-07-29 09:52:21 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072939-CVE-2026-64556-0f2c@gregkh/T