On 2024/8/13 18:47, Greg KH wrote: > On Tue, Aug 06, 2024 at 07:16:16AM +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. > > You forgot a 5.15.y version, which is of course required if we were to > take a 5.10.y version :( > > Please resubmit both. Sorry for forgetting the 5.15.y, I'll resend it sooner, thank you! > > thanks, > > greg k-h
