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.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
eb553f16973ade990d05946af9ae191394712c8a to < fb6675db04c4b79883373edc578d5df7bbc84848affectedeb553f16973ade990d05946af9ae191394712c8a to < e2afb26615adf6c3ceaaa7732aa839bcd587a057affectedeb553f16973ade990d05946af9ae191394712c8a to < 8d3f83dfb23674540c827a8d65fba20aa300b252affectedeb553f16973ade990d05946af9ae191394712c8a to < 0f37946c62c48a907625348cbc720a7a0c547d1eaffectedeb553f16973ade990d05946af9ae191394712c8a to < 2c78c9411e685dbc9eac8c2845111b03501975b8affectedeb553f16973ade990d05946af9ae191394712c8a to < 0db880fc865ffb522141ced4bfa66c12ab1fbb70affected
Linux Linux
Default version status: affected
5.10affected0 to < 5.10unaffected5.10.224 to ≤ 5.10.*unaffected5.15.165 to ≤ 5.15.*unaffected6.1.98 to ≤ 6.1.*unaffected6.6.39 to ≤ 6.6.*unaffected6.9.9 to ≤ 6.9.*unaffected6.10 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/fb6675db04c4b79883373edc578d5df7bbc84848 ↗
- https://git.kernel.org/stable/c/e2afb26615adf6c3ceaaa7732aa839bcd587a057 ↗
- https://git.kernel.org/stable/c/8d3f83dfb23674540c827a8d65fba20aa300b252 ↗
- https://git.kernel.org/stable/c/0f37946c62c48a907625348cbc720a7a0c547d1e ↗
- https://git.kernel.org/stable/c/2c78c9411e685dbc9eac8c2845111b03501975b8 ↗
- https://git.kernel.org/stable/c/0db880fc865ffb522141ced4bfa66c12ab1fbb70 ↗
- https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html ↗