GHSA-VX4J-2P26-Q8M4
Vulnerability from github – Published: 2024-07-30 09:32 – Updated: 2025-11-04 00:31In 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.
{
"affected": [],
"aliases": [
"CVE-2024-42126"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-07-30T08:15:04Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc: Avoid nmi_enter/nmi_exit in real mode interrupt.\n\nnmi_enter()/nmi_exit() touches per cpu variables which can lead to kernel\ncrash when invoked during real mode interrupt handling (e.g. early HMI/MCE\ninterrupt handler) if percpu allocation comes from vmalloc area.\n\nEarly HMI/MCE handlers are called through DEFINE_INTERRUPT_HANDLER_NMI()\nwrapper which invokes nmi_enter/nmi_exit calls. We don\u0027t see any issue when\npercpu allocation is from the embedded first chunk. However with\nCONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpu\nallocation can come from the vmalloc area.\n\nWith kernel command line \"percpu_alloc=page\" we can force percpu allocation\nto come from vmalloc area and can see kernel crash in machine_check_early:\n\n[ 1.215714] NIP [c000000000e49eb4] rcu_nmi_enter+0x24/0x110\n[ 1.215717] LR [c0000000000461a0] machine_check_early+0xf0/0x2c0\n[ 1.215719] --- interrupt: 200\n[ 1.215720] [c000000fffd73180] [0000000000000000] 0x0 (unreliable)\n[ 1.215722] [c000000fffd731b0] [0000000000000000] 0x0\n[ 1.215724] [c000000fffd73210] [c000000000008364] machine_check_early_common+0x134/0x1f8\n\nFix this by avoiding use of nmi_enter()/nmi_exit() in real mode if percpu\nfirst chunk is not embedded.",
"id": "GHSA-vx4j-2p26-q8m4",
"modified": "2025-11-04T00:31:06Z",
"published": "2024-07-30T09:32:01Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-42126"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0db880fc865ffb522141ced4bfa66c12ab1fbb70"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0f37946c62c48a907625348cbc720a7a0c547d1e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2c78c9411e685dbc9eac8c2845111b03501975b8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8d3f83dfb23674540c827a8d65fba20aa300b252"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e2afb26615adf6c3ceaaa7732aa839bcd587a057"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fb6675db04c4b79883373edc578d5df7bbc84848"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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