On Tue, Aug 13, 2024 at 11:33:44AM +0000, Jinjie Ruan wrote: > From: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxx> > > [ Upstream commit 0db880fc865ffb522141ced4bfa66c12ab1fbb70 ] > > 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. > > CVE-2024-42126 > Cc: stable@xxxxxxxxxxxxxxx#5.10.x > Cc: gregkh@xxxxxxxxxxxxxxxxxxx > Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx> > Tested-by: Shirisha Ganta <shirisha@xxxxxxxxxxxxx> > Signed-off-by: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxx> > Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> > Link: https://msgid.link/20240410043006.81577-1-mahesh@xxxxxxxxxxxxx > [ Conflicts in arch/powerpc/include/asm/interrupt.h > because machine_check_early() and machine_check_exception() > has been refactored. ] > Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx> > --- > v2: > - Also fix for CONFIG_PPC_BOOK3S_64 not enabled. > - Add Upstream. > - Cc stable@xxxxxxxxxxxxxxx. > --- Both now queued up, thanks. greg k-h
