ghsa-vx4j-2p26-q8m4
Vulnerability from github
Published
2024-07-30 09:32
Modified
2024-08-19 06:30
Details

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.

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{
   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: null,
   },
   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't 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: "2024-08-19T06:30:52Z",
   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",
      },
   ],
   schema_version: "1.4.0",
   severity: [],
}


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