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Bug#1095435: linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot

Started by	Andrew Kanaber <adk-debianbugs@jump.net.uk>
First post	2025-02-07 22:30 +0100
Last post	2025-02-18 13:40 +0100
Articles	4 — 3 participants

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  Bug#1095435: linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot Andrew Kanaber <adk-debianbugs@jump.net.uk> - 2025-02-07 22:30 +0100
    Bug#1095435: linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot Salvatore Bonaccorso <carnil@debian.org> - 2025-02-08 16:50 +0100
    Processed: Re: Bug#1095435: linux-source-6.1: fixes for XSA-466  (in linux 6.1.121+) can break Xen PVH domU boot "Debian Bug Tracking System" <owner@bugs.debian.org> - 2025-02-08 16:50 +0100
    Bug#1095435: marked as done (linux-source-6.1: fixes for XSA-466  (in linux 6.1.121+) can break Xen PVH domU boot) "Debian Bug Tracking System" <owner@bugs.debian.org> - 2025-02-18 13:40 +0100

#85417 — Bug#1095435: linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot

From	Andrew Kanaber <adk-debianbugs@jump.net.uk>
Date	2025-02-07 22:30 +0100
Subject	Bug#1095435: linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot
Message-ID	<KdE5b-fa4i-7@gated-at.bofh.it>

Package: linux-source-6.1
Version: 6.1.124-1
Severity: critical
Justification: breaks the whole system
Tags: patch

Hi,

It turns out the upstream changes made to fix XSA-466 / CVE-2024-53241
"x86/xen: remove hypercall page" [1] and
"x86/xen: use new hypercall functions instead of hypercall page" [2]
can leave an Xen PVH domU unbootable. These went into Debian in
linux-image-6.1.0-29-amd64 (6.1.123-1) and upstream Linux in 6.1.121,
and also into other kernel series, and mainline.

Juergen Gross has already very helpfully diagnosed this problem and
fixed it with a patch that's been accepted in mainline
"x86/xen: fix xen_hypercall_hvm() to not clobber %rbx" [3]

This bug report is to request this patch be incorporated into the Debian
stable kernel.

It seems quite variable whether systems are affected. Not everyone hits
it, but we (Jump Networks, a VPS hosting provider) have seen it across
multiple versions of Xen and on both Intel and AMD hardware. Symptoms
are PVH domU immediately shutting down before any output from the
kernel, even with earlyprintk=xen and CONFIG_X86_VERBOSE_BOOTUP. The xl
log just shows that the domain shut down.

Appending 'loglvl=all guest_loglvl=all' to the Xen host commandline 
produces something more useful in the 'xl dmesg' buffer after a guest
crash, here's some characteristic output for anyone else wanting to know
if they're hitting the same bug (garbled characters in original, and bug
related).

(d38) [    0.000000] Linux version 6.1.0-29-amd64 (debian-kernel@lists.debian.org) (gcc-12 (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40) #1 SMP PREEMPT_DYNAMIC Debian 6.1.123-1 (2025-01
(d38) -02)
(d38) @�!��������Linux version 6.1.0-29-amd64 (debian-kernel@lists.debian.org) (gcc-12 (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40) #1 SMP PREEMPT_DYNAMIC Debian 6.1.123-1 (2025-01-02)
(d38) 2)
(d38) ���Command line: BOOT_IMAGE=/boot/vmlinuz-6.1.0-29-amd64 root=PARTUUID=5650c9f4-01 ro console=tty0 console=hvc0 earlyprintk=xen net.ifnames=0 consoleblank=0=0
(d38) ���BIOS-provided physical RAM map:p:
(d38) ���BIOS-e820: [mem 0x0000000000000000-0x00000000fbffffff] usablec
(d38) ���BIOS-e820: [mem 0x00000000fc000000-0x00000000fc008fff] ACPI datac
(d38) ���BIOS-e820: [mem 0x00000000feff8000-0x00000000feffffff] reservedc
(d38) ���BIOS-e820: [mem 0x0000000100000000-0x0000000203ffffff] usablec
(d38) �?Ħ���� @Ħ�����AĦ�����AĦ�����AĦ����BĦ����CĦ����@CĦ����DĦ�����DĦ�����DĦ�����DĦ�����DĦ�����DĦ����EĦ����IĦ����IĦ����@IĦ����`IĦ�����JĦ�����JĦ�����JĦ�����JĦ����@KĦ����KĦ�����KĦ��
(d38) ���KĦ�����KĦ�����KĦ����LĦ����LĦ���� LĦ����PLĦ����`LĦ����pLĦ����LĦ����LĦ�����LĦ�����LĦ�����LĦ�����LĦ�����LĦ����MĦ����MĦ���� MĦ����@MĦ����pRĦ����pSĦ����SĦ�����SĦ����UĦ����PUĦ�
(d38) ����UĦ����@Ħ�����Ħ����PĦ����`Ħ�����Ħ����`�Ħ�����Ħ�����Ħ�����Ħ����@�Ħ����`�Ħ����p�Ħ�����Ħ�����Ħ������Ħ������Ħ������Ħ����гĦ�����Ħ����`�Ħ�����Ħ�����Ħ����@�Ħ����P�Ħ����p�Ħ���
(d38) ��Ħ�����Ħ�����Ħ���� �Ħ����0�Ħ����P�Ħ�����Ħ������Ħ����жĦ����0�Ħ�����Ħ������Ħ�����Ħ����p�Ħ����`�Ħ������Ħ���� �Ħ����@�Ħ����PANIC: early exception 0x0e IP 10:ffffffffa5e9606b error 0 c
(d38) r2 0xffffffffa8e00000

Thanks for your help,

Andrew Kanaber
Jump Networks

[1] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4c24703978b44d4bb95413a6b85c3254a5fa9bc1

[2] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1a2471af32acd00378d07164d025eaf226f337c3

[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/x86/xen/xen-head.S?id=98a5cfd2320966f40fe049a9855f8787f0126825

-- System Information:
Debian Release: 12.9
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 6.1.128 (SMP w/8 CPU threads; PREEMPT)
Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages linux-source-6.1 depends on:
ii  binutils  2.40-2
ii  xz-utils  5.4.1-0.2

Versions of packages linux-source-6.1 recommends:
ii  bc                1.07.1-3+b1
ii  bison             2:3.8.2+dfsg-1+b1
ii  build-essential   12.9
ii  cpio              2.13+dfsg-7.1
ii  flex              2.6.4-8.2
ii  kmod              30+20221128-1
ii  libelf-dev        0.188-2.1
ii  libssl-dev        3.0.15-1~deb12u1
ii  linux-config-6.1  6.1.124-1
ii  rsync             3.2.7-1+deb12u2

Versions of packages linux-source-6.1 suggests:
ii  libncurses-dev [ncurses-dev]  6.4-4
pn  pkg-config                    <none>
pn  qtbase5-dev                   <none>

-- no debconf information

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#85431

From	Salvatore Bonaccorso <carnil@debian.org>
Date	2025-02-08 16:50 +0100
Message-ID	<KdVfH-fkQc-7@gated-at.bofh.it>
In reply to	#85417

Control: tags -1 + fixed-upstream confirmed

Hi 

On Fri, Feb 07, 2025 at 09:03:25PM +0000, Andrew Kanaber wrote:
> Package: linux-source-6.1
> Version: 6.1.124-1
> Severity: critical
> Justification: breaks the whole system
> Tags: patch
> 
> Hi,
> 
> It turns out the upstream changes made to fix XSA-466 / CVE-2024-53241
> "x86/xen: remove hypercall page" [1] and
> "x86/xen: use new hypercall functions instead of hypercall page" [2]
> can leave an Xen PVH domU unbootable. These went into Debian in
> linux-image-6.1.0-29-amd64 (6.1.123-1) and upstream Linux in 6.1.121,
> and also into other kernel series, and mainline.
> 
> Juergen Gross has already very helpfully diagnosed this problem and
> fixed it with a patch that's been accepted in mainline
> "x86/xen: fix xen_hypercall_hvm() to not clobber %rbx" [3]
> 
> This bug report is to request this patch be incorporated into the Debian
> stable kernel.

Thanks for the report. Debian is following the 6.1.y stable series, so
once the patch has been submitted and accepted for stable into 6.1.y
we will pick it up automatically and incorporate it in the respective
upload.

Regards,
Salvtore

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#85432 — Processed: Re: Bug#1095435: linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot

From	"Debian Bug Tracking System" <owner@bugs.debian.org>
Date	2025-02-08 16:50 +0100
Subject	Processed: Re: Bug#1095435: linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot
Message-ID	<KdVfI-fkQc-25@gated-at.bofh.it>
In reply to	#85417

Processing control commands:

> tags -1 + fixed-upstream confirmed
Bug #1095435 [src:linux] linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot
Added tag(s) fixed-upstream and confirmed.

-- 
1095435: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1095435
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems

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#85532 — Bug#1095435: marked as done (linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot)

From	"Debian Bug Tracking System" <owner@bugs.debian.org>
Date	2025-02-18 13:40 +0100
Subject	Bug#1095435: marked as done (linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot)
Message-ID	<Khv3m-8nE-47@gated-at.bofh.it>
In reply to	#85417

[Multipart message — attachments visible in raw view] — view raw

Your message dated Tue, 18 Feb 2025 12:30:36 +0000
with message-id <E1tkMkG-004lwz-2b@fasolo.debian.org>
and subject line Bug#1095435: fixed in linux 6.13.3-1~exp1
has caused the Debian Bug report #1095435,
regarding linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact owner@bugs.debian.org
immediately.)


-- 
1095435: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1095435
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems

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Bug#1095435: linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot

Contents

#85417 — Bug#1095435: linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot

#85431

#85432 — Processed: Re: Bug#1095435: linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot

#85532 — Bug#1095435: marked as done (linux-source-6.1: fixes for XSA-466 (in linux 6.1.121+) can break Xen PVH domU boot)