Oracle Linux: CVE-2024-42126: ELSA-2024-12815: Unbreakable Enterprise kernel security update (IMPORTANT) (Multiple Advisories)

Oracle Linux: CVE-2024-42126: ELSA-2024-12815: Unbreakable Enterprise kernel security update (IMPORTANT) (Multiple Advisories)

Severity

4

CVSS

(AV:L/AC:L/Au:M/C:N/I:N/A:C)

Published

07/30/2024

Created

11/23/2024

Added

11/21/2024

Modified

01/23/2025

Description

In the Linux kernel, the following vulnerability has been resolved: powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt. nmi_enter()/nmi_exit() touches per cpu variables which can lead to kernel crash when invoked during real mode interrupt handling (e.g. early HMI/MCE interrupt handler) if percpu allocation comes from vmalloc area. Early HMI/MCE handlers are called through DEFINE_INTERRUPT_HANDLER_NMI() wrapper which invokes nmi_enter/nmi_exit calls. We don't see any issue when percpu allocation is from the embedded first chunk. However with CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpu allocation can come from the vmalloc area. With kernel command line "percpu_alloc=page" we can force percpu allocation to come from vmalloc area and can see kernel crash in machine_check_early: [1.215714] NIP [c000000000e49eb4] rcu_nmi_enter+0x24/0x110 [1.215717] LR [c0000000000461a0] machine_check_early+0xf0/0x2c0 [1.215719] --- interrupt: 200 [1.215720] [c000000fffd73180] [0000000000000000] 0x0 (unreliable) [1.215722] [c000000fffd731b0] [0000000000000000] 0x0 [1.215724] [c000000fffd73210] [c000000000008364] machine_check_early_common+0x134/0x1f8 Fix this by avoiding use of nmi_enter()/nmi_exit() in real mode if percpu first chunk is not embedded.

Solution(s)

• oracle-linux-upgrade-kernel-uek

References

• https://attackerkb.com/topics/cve-2024-42126
• CVE - 2024-42126
• ELSA-2024-12815