Bug 2492411 (CVE-2026-53106)

Summary: CVE-2026-53106 kernel: bpf: Do not allow deleting local storage in NMI
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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OS: Linux   
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A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) local storage. This vulnerability can lead to a system deadlock when local storage is deleted within a Non-Maskable Interrupt (NMI) context. An attacker could potentially exploit this by triggering the deletion of BPF local storage during an NMI, resulting in a denial of service.
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Description OSIDB Bzimport 2026-06-24 18:10:49 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bpf: Do not allow deleting local storage in NMI

Currently, local storage may deadlock when deferring freeing selem or
local storage through kfree_rcu(), call_rcu() or call_rcu_tasks_trace()
in NMI or reentrant. Since deleting selem in NMI is an unlikely use
case, partially mitigate it by returning error when calling from
bpf_xxx_storage_delete() helpers in NMI. Note that, it is still possible
to deadlock through reentrant. A full mitigation requires returning
error when irqs_disabled() is true, which, however is too heavy-handed
for bpf_xxx_storage_delete().

The long-term solution requires _nolock versions of call_rcu. Another
possible solution is to defer the free through irq_work [0], but it
would grow the size of selem, which is non-ideal.

The check is only needed in bpf_selem_unlink(), which is used by helpers
and syscalls. bpf_selem_unlink_nofail() is fine as it is called during
map and owner tear down that never run in NMI or reentrant.

[0] https://lore.kernel.org/bpf/20260205190233.912-1-alexei.starovoitov@gmail.com/
Comment 1 Mauro Matteo Cascella 2026-06-26 12:20:20 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062413-CVE-2026-53106-3a3d@gregkh/T