From: Salvatore Bonaccorso <carnil@debian.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: oss-security@lists.openwall.com, linuxppc-dev@lists.ozlabs.org,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Subject: Re: [oss-security] Linux kernel: powerpc: KVM guest can trigger host crash on Power8
Date: Thu, 28 Oct 2021 05:58:05 +0200 [thread overview]
Message-ID: <YXofzUCGm3N7lfNf@elende.valinor.li> (raw)
In-Reply-To: <87pmrtbbdt.fsf@mpe.ellerman.id.au>
Hi,
On Mon, Oct 25, 2021 at 10:18:54PM +1100, Michael Ellerman wrote:
> The Linux kernel for powerpc since v5.2 has a bug which allows a
> malicious KVM guest to crash the host, when the host is running on
> Power8.
>
> Only machines using Linux as the hypervisor, aka. KVM, powernv or bare
> metal, are affected by the bug. Machines running PowerVM are not
> affected.
>
> The bug was introduced in:
>
> 10d91611f426 ("powerpc/64s: Reimplement book3s idle code in C")
>
> Which was first released in v5.2.
>
> The upstream fix is:
>
> cdeb5d7d890e ("KVM: PPC: Book3S HV: Make idle_kvm_start_guest() return 0 if it went to guest")
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cdeb5d7d890e14f3b70e8087e745c4a6a7d9f337
>
> Which will be included in the v5.16 release.
>
> Note to backporters, the following commits are required:
>
> 73287caa9210ded6066833195f4335f7f688a46b
> ("powerpc64/idle: Fix SP offsets when saving GPRs")
>
> 9b4416c5095c20e110c82ae602c254099b83b72f
> ("KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest()")
>
> cdeb5d7d890e14f3b70e8087e745c4a6a7d9f337
> ("KVM: PPC: Book3S HV: Make idle_kvm_start_guest() return 0 if it went to guest")
>
> 496c5fe25c377ddb7815c4ce8ecfb676f051e9b6
> ("powerpc/idle: Don't corrupt back chain when going idle")
>
>
> I have a test case to trigger the bug, which I can share privately with
> anyone who would like to test the fix.
The issue has been assigned CVE-2021-43056.
Regards,
Salvatore
prev parent reply other threads:[~2021-10-28 6:00 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-25 11:18 Linux kernel: powerpc: KVM guest can trigger host crash on Power8 Michael Ellerman
2021-10-26 8:48 ` John Paul Adrian Glaubitz
2021-10-27 5:29 ` Nicholas Piggin
2021-10-27 5:30 ` Michael Ellerman
2021-10-27 10:03 ` John Paul Adrian Glaubitz
2021-10-27 11:06 ` Michael Ellerman
2021-10-27 11:09 ` John Paul Adrian Glaubitz
2021-10-28 6:39 ` Michael Ellerman
2021-10-28 11:20 ` John Paul Adrian Glaubitz
2021-10-28 14:05 ` John Paul Adrian Glaubitz
2021-10-28 14:15 ` John Paul Adrian Glaubitz
2021-11-01 17:36 ` Michal Suchánek
2021-10-29 0:41 ` Nicholas Piggin
2021-10-29 12:33 ` John Paul Adrian Glaubitz
2021-11-01 17:43 ` Michal Suchánek
2021-10-30 7:19 ` John Paul Adrian Glaubitz
2021-11-01 6:53 ` Michael Ellerman
2021-11-01 7:37 ` John Paul Adrian Glaubitz
2021-11-01 17:20 ` John Paul Adrian Glaubitz
2022-01-04 13:00 ` John Paul Adrian Glaubitz
2022-01-06 10:58 ` Michael Ellerman
2022-01-07 11:20 ` John Paul Adrian Glaubitz
2022-01-09 22:17 ` John Paul Adrian Glaubitz
2022-01-13 0:17 ` John Paul Adrian Glaubitz
2022-01-26 20:21 ` John Paul Adrian Glaubitz
2022-01-27 15:50 ` Mike
2021-10-28 13:52 ` John Paul Adrian Glaubitz
2021-10-28 14:00 ` John Paul Adrian Glaubitz
2021-10-28 3:58 ` Salvatore Bonaccorso [this message]
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