CVE-2024-42126

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 kernelcrash when invoked during real mode interrupt handling (e.g. early HMI/MCEinterrupt 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 dont see any issue whenpercpu allocation is from the embedded first chunk. However withCONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpuallocation can come from the vmalloc area.With kernel command line percpu_alloc=page we can force percpu allocationto 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+0x134/0x1f8Fix this by avoiding use of nmi_enter()/nmi_exit() in real mode if percpufirst chunk is not embedded.

Risk Information

Associated Vulnerability

Patch Details

References

https://nvd.nist.gov/vuln/detail/CVE-2023-1234
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-1234