Upstream information
Description
In the Linux kernel, the following vulnerability has been resolved:fbdev: hyperv_fb: Fix hang in kdump kernel when on Hyper-V Gen 2 VMs
Gen 2 Hyper-V VMs boot via EFI and have a standard EFI framebuffer
device. When the kdump kernel runs in such a VM, loading the efifb
driver may hang because of accessing the framebuffer at the wrong
memory address.
The scenario occurs when the hyperv_fb driver in the original kernel
moves the framebuffer to a different MMIO address because of conflicts
with an already-running efifb or simplefb driver. The hyperv_fb driver
then informs Hyper-V of the change, which is allowed by the Hyper-V FB
VMBus device protocol. However, when the kexec command loads the kdump
kernel into crash memory via the kexec_file_load() system call, the
system call doesn't know the framebuffer has moved, and it sets up the
kdump screen_info using the original framebuffer address. The transition
to the kdump kernel does not go through the Hyper-V host, so Hyper-V
does not reset the framebuffer address like it would do on a reboot.
When efifb tries to run, it accesses a non-existent framebuffer
address, which traps to the Hyper-V host. After many such accesses,
the Hyper-V host thinks the guest is being malicious, and throttles
the guest to the point that it runs very slowly or appears to have hung.
When the kdump kernel is loaded into crash memory via the kexec_load()
system call, the problem does not occur. In this case, the kexec command
builds the screen_info table itself in user space from data returned
by the FBIOGET_FSCREENINFO ioctl against /dev/fb0, which gives it the
new framebuffer location.
This problem was originally reported in 2020 [1], resulting in commit
3cb73bc3fa2a ("hyperv_fb: Update screen_info after removing old
framebuffer"). This commit solved the problem by setting orig_video_isVGA
to 0, so the kdump kernel was unaware of the EFI framebuffer. The efifb
driver did not try to load, and no hang occurred. But in 2024, commit
c25a19afb81c ("fbdev/hyperv_fb: Do not clear global screen_info")
effectively reverted 3cb73bc3fa2a. Commit c25a19afb81c has no reference
to 3cb73bc3fa2a, so perhaps it was done without knowing the implications
that were reported with 3cb73bc3fa2a. In any case, as of commit
c25a19afb81c, the original problem came back again.
Interestingly, the hyperv_drm driver does not have this problem because
it never moves the framebuffer. The difference is that the hyperv_drm
driver removes any conflicting framebuffers *before* allocating an MMIO
address, while the hyperv_fb drivers removes conflicting framebuffers
*after* allocating an MMIO address. With the "after" ordering, hyperv_fb
may encounter a conflict and move the framebuffer to a different MMIO
address. But the conflict is essentially bogus because it is removed
a few lines of code later.
Rather than fix the problem with the approach from 2020 in commit
3cb73bc3fa2a, instead slightly reorder the steps in hyperv_fb so
conflicting framebuffers are removed before allocating an MMIO address.
Then the default framebuffer MMIO address should always be available, and
there's never any confusion about which framebuffer address the kdump
kernel should use -- it's always the original address provided by
the Hyper-V host. This approach is already used by the hyperv_drm
driver, and is consistent with the usage guidelines at the head of
the module with the function aperture_remove_conflicting_devices().
This approach also solves a related minor problem when kexec_load()
is used to load the kdump kernel. With current code, unbinding and
rebinding the hyperv_fb driver could result in the framebuffer moving
back to the default framebuffer address, because on the rebind there
are no conflicts. If such a move is done after the kdump kernel is
loaded with the new framebuffer address, at kdump time it could again
have the wrong address.
This problem and fix are described in terms of the kdump kernel, but
it can also occur
---truncated---
SUSE information
Overall state of this security issue: Pending
This issue is currently rated as having moderate severity.
| SUSE | |
|---|---|
| Base Score | 5.5 |
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| Attack Vector | Local |
| Attack Complexity | Low |
| Privileges Required | Low |
| User Interaction | None |
| Scope | Unchanged |
| Confidentiality Impact | None |
| Integrity Impact | None |
| Availability Impact | High |
| CVSSv3 Version | 3.1 |
| SUSE | |
|---|---|
| Base Score | 5.7 |
| Vector | CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| Attack Vector | Local |
| Attack Complexity | Low |
| Attack Requirements | Present |
| Privileges Required | Low |
| User Interaction | None |
| Vulnerable System Confidentiality Impact | None |
| Vulnerable System Integrity Impact | None |
| Vulnerable System Availability Impact | High |
| Subsequent System Confidentiality Impact | None |
| Subsequent System Integrity Impact | None |
| Subsequent System Availability Impact | None |
| CVSSv4 Version | 4.0 |
Note from the SUSE Security Team on the kernel-default package
SUSE will no longer fix all CVEs in the Linux Kernel anymore, but declare some bug classes as won't fix. Please refer to TID 21496 for more details.SUSE Bugzilla entry: 1240876 [NEW]
No SUSE Security Announcements cross referenced.
Status of this issue by product and package
Please note that this evaluation state might be work in progress, incomplete or outdated. Also information for service packs in the LTSS phase is only included for issues meeting the LTSS criteria. If in doubt, feel free to contact us for clarification. The updates are grouped by state of their lifecycle. SUSE product lifecycles are documented on the lifecycle page.
| Product(s) | Source package | State |
|---|---|---|
| Products under general support and receiving all security fixes. | ||
| SUSE Linux Enterprise Desktop 15 SP6 | kernel-default | Not affected |
| SUSE Linux Enterprise Desktop 15 SP6 | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | kernel-default | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | kernel-source-azure | Affected |
| SUSE Linux Enterprise Live Patching 15 SP6 | kernel-default | Not affected |
| SUSE Linux Enterprise Live Patching 15 SP6 | kernel-source | Not affected |
| SUSE Linux Enterprise Micro 5.1 | kernel-default | Affected |
| SUSE Linux Enterprise Micro 5.1 | kernel-rt | Affected |
| SUSE Linux Enterprise Micro 5.1 | kernel-source | Affected |
| SUSE Linux Enterprise Micro 5.1 | kernel-source-rt | Affected |
| SUSE Linux Enterprise Micro 5.2 | kernel-default | Affected |
| SUSE Linux Enterprise Micro 5.2 | kernel-rt | Affected |
| SUSE Linux Enterprise Micro 5.2 | kernel-source | Affected |
| SUSE Linux Enterprise Micro 5.2 | kernel-source-rt | Affected |
| SUSE Linux Enterprise Micro 5.3 | kernel-default | Not affected |
| SUSE Linux Enterprise Micro 5.3 | kernel-rt | Not affected |
| SUSE Linux Enterprise Micro 5.3 | kernel-source | Not affected |
| SUSE Linux Enterprise Micro 5.3 | kernel-source-rt | Not affected |
| SUSE Linux Enterprise Micro 5.4 | kernel-default | Not affected |
| SUSE Linux Enterprise Micro 5.4 | kernel-rt | Not affected |
| SUSE Linux Enterprise Micro 5.4 | kernel-source | Not affected |
| SUSE Linux Enterprise Micro 5.4 | kernel-source-rt | Not affected |
| SUSE Linux Enterprise Micro 5.5 | kernel-default | Not affected |
| SUSE Linux Enterprise Micro 5.5 | kernel-source | Not affected |
| SUSE Linux Enterprise Micro 5.5 | kernel-source-rt | Not affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP6 | kernel-default | Not affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP6 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP6 | kernel-default | Not affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP6 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Public Cloud 15 SP6 | kernel-source-azure | Affected |
| SUSE Linux Enterprise Real Time 15 SP6 | kernel-source-rt | Not affected |
| SUSE Linux Enterprise Server 15 SP6 | kernel-default | Not affected |
| SUSE Linux Enterprise Server 15 SP6 | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP6 | kernel-source-azure | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | kernel-source | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | kernel-source-azure | Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP6 | kernel-default | Not affected |
| SUSE Linux Enterprise Workstation Extension 15 SP6 | kernel-source | Not affected |
| SUSE Linux Micro 6.0 | kernel-default | Affected |
| SUSE Linux Micro 6.0 | kernel-source | Affected |
| SUSE Linux Micro 6.0 | kernel-source-rt | Affected |
| SUSE Linux Micro 6.1 | kernel-default | Affected |
| SUSE Linux Micro 6.1 | kernel-source | Affected |
| SUSE Linux Micro 6.1 | kernel-source-rt | Affected |
| SUSE Manager Proxy 4.3 | kernel-default | Not affected |
| SUSE Manager Proxy 4.3 | kernel-source | Not affected |
| SUSE Manager Retail Branch Server 4.3 | kernel-default | Not affected |
| SUSE Manager Retail Branch Server 4.3 | kernel-source | Not affected |
| SUSE Manager Server 4.3 | kernel-default | Not affected |
| SUSE Manager Server 4.3 | kernel-source | Not affected |
| SUSE Real Time Module 15 SP6 | kernel-source-rt | Not affected |
| openSUSE Leap 15.6 | kernel-default | Not affected |
| openSUSE Leap 15.6 | kernel-source | Not affected |
| openSUSE Leap 15.6 | kernel-source-azure | Affected |
| openSUSE Leap 15.6 | kernel-source-rt | Not affected |
| Products under Long Term Service Pack support and receiving important and critical security fixes. | ||
| SUSE Linux Enterprise High Performance Computing 15 SP3 | kernel-source | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | kernel-source | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-default | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | kernel-source-azure | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-default | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Live Patching 12 SP5 | kernel-default | Affected |
| SUSE Linux Enterprise Live Patching 12 SP5 | kernel-source | Affected |
| SUSE Linux Enterprise Live Patching 15 SP3 | kernel-default | Affected |
| SUSE Linux Enterprise Live Patching 15 SP3 | kernel-source | Affected |
| SUSE Linux Enterprise Live Patching 15 SP4 | kernel-default | Not affected |
| SUSE Linux Enterprise Live Patching 15 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise Live Patching 15 SP5 | kernel-default | Not affected |
| SUSE Linux Enterprise Live Patching 15 SP5 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP3 | kernel-source | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP5 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP3 | kernel-source | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP5 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Public Cloud 15 SP5 | kernel-source-azure | Not affected |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | kernel-default | Affected |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | kernel-source | Affected |
| SUSE Linux Enterprise Server 12 SP5 | kernel-source | Affected |
| SUSE Linux Enterprise Server 12 SP5 | kernel-source-azure | Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-default | Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-source-azure | Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | kernel-default | Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | kernel-source | Affected |
| SUSE Linux Enterprise Server 15 SP3 | kernel-source | Affected |
| SUSE Linux Enterprise Server 15 SP3-LTSS | kernel-default | Affected |
| SUSE Linux Enterprise Server 15 SP3-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise Server 15 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP5 | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP5 | kernel-source-azure | Not affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 | kernel-source | Affected |
| SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 | kernel-source-azure | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | kernel-default | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | kernel-source | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | kernel-default | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | kernel-source | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | kernel-source-azure | Not affected |
| Products past their end of life and not receiving proactive updates anymore. | ||
| SUSE CaaS Platform 4.0 | kernel-source | Affected |
| SUSE Enterprise Storage 6 | kernel-source | Affected |
| SUSE Enterprise Storage 7 | kernel-source | Affected |
| SUSE Enterprise Storage 7.1 | kernel-source | Affected |
| SUSE Linux Enterprise Desktop 11 SP4 | kernel-source | Affected |
| SUSE Linux Enterprise Desktop 12 SP2 | kernel-source | Affected |
| SUSE Linux Enterprise Desktop 12 SP4 | kernel-source | Affected |
| SUSE Linux Enterprise Desktop 15 | kernel-source | Affected |
| SUSE Linux Enterprise Desktop 15 SP1 | kernel-source | Affected |
| SUSE Linux Enterprise Desktop 15 SP2 | kernel-source | Affected |
| SUSE Linux Enterprise Desktop 15 SP3 | kernel-source | Affected |
| SUSE Linux Enterprise Desktop 15 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise Desktop 15 SP5 | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 | kernel-source | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1 | kernel-source | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS | kernel-source | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | kernel-source | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | kernel-source | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15-ESPOS | kernel-source | Affected |
| SUSE Linux Enterprise High Performance Computing 15-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise Micro 5.0 | kernel-default | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 | kernel-source | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP1 | kernel-source | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP2 | kernel-source | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 | kernel-source | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP1 | kernel-source | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP2 | kernel-source | Affected |
| SUSE Linux Enterprise Point of Sale 12 SP2-CLIENT | kernel-source | Affected |
| SUSE Linux Enterprise Real Time 15 SP2 | kernel-source | Affected |
| SUSE Linux Enterprise Real Time 15 SP3 | kernel-source | Affected |
| SUSE Linux Enterprise Real Time 15 SP3 | kernel-source-rt | Affected |
| SUSE Linux Enterprise Real Time 15 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise Real Time 15 SP4 | kernel-source-rt | Not affected |
| SUSE Linux Enterprise Real Time 15 SP5 | kernel-source-rt | Not affected |
| SUSE Linux Enterprise Server 11 SP4 | kernel-source | Affected |
| SUSE Linux Enterprise Server 11 SP4 LTSS | kernel-default | Affected |
| SUSE Linux Enterprise Server 11 SP4 LTSS | kernel-source | Affected |
| SUSE Linux Enterprise Server 11 SP4-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise Server 12 SP2 | kernel-source | Affected |
| SUSE Linux Enterprise Server 12 SP2-BCL | kernel-source | Affected |
| SUSE Linux Enterprise Server 12 SP2-ESPOS | kernel-source | Affected |
| SUSE Linux Enterprise Server 12 SP2-LTSS | kernel-default | Affected |
| SUSE Linux Enterprise Server 12 SP2-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise Server 12 SP4 | kernel-source | Affected |
| SUSE Linux Enterprise Server 12 SP4-ESPOS | kernel-source | Affected |
| SUSE Linux Enterprise Server 12 SP4-LTSS | kernel-default | Affected |
| SUSE Linux Enterprise Server 12 SP4-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise Server 15 | kernel-source | Affected |
| SUSE Linux Enterprise Server 15 SP1 | kernel-source | Affected |
| SUSE Linux Enterprise Server 15 SP1-BCL | kernel-source | Affected |
| SUSE Linux Enterprise Server 15 SP1-LTSS | kernel-default | Affected |
| SUSE Linux Enterprise Server 15 SP1-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise Server 15 SP2 | kernel-source | Affected |
| SUSE Linux Enterprise Server 15 SP2-BCL | kernel-source | Affected |
| SUSE Linux Enterprise Server 15 SP2-LTSS | kernel-default | Affected |
| SUSE Linux Enterprise Server 15 SP2-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise Server 15 SP3-BCL | kernel-source | Affected |
| SUSE Linux Enterprise Server 15-LTSS | kernel-default | Affected |
| SUSE Linux Enterprise Server 15-LTSS | kernel-source | Affected |
| SUSE Linux Enterprise Server for Raspberry Pi 12 SP2 | kernel-source | Affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP2 | kernel-source | Affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP4 | kernel-source | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 | kernel-source | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP1 | kernel-source | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | kernel-source | Affected |
| SUSE Manager Proxy 4.0 | kernel-source | Affected |
| SUSE Manager Proxy 4.1 | kernel-source | Affected |
| SUSE Manager Proxy 4.2 | kernel-source | Affected |
| SUSE Manager Retail Branch Server 4.0 | kernel-source | Affected |
| SUSE Manager Retail Branch Server 4.1 | kernel-source | Affected |
| SUSE Manager Retail Branch Server 4.2 | kernel-source | Affected |
| SUSE Manager Server 4.0 | kernel-source | Affected |
| SUSE Manager Server 4.1 | kernel-source | Affected |
| SUSE Manager Server 4.2 | kernel-source | Affected |
| SUSE OpenStack Cloud 7 | kernel-source | Affected |
| SUSE OpenStack Cloud 9 | kernel-source | Affected |
| SUSE OpenStack Cloud Crowbar 9 | kernel-source | Affected |
| SUSE Real Time Module 15 SP3 | kernel-source-rt | Affected |
| SUSE Real Time Module 15 SP4 | kernel-source-rt | Not affected |
| SUSE Real Time Module 15 SP5 | kernel-source-rt | Not affected |
| openSUSE Leap 15.3 | kernel-source | Affected |
| openSUSE Leap 15.3 | kernel-source-rt | Affected |
| openSUSE Leap 15.4 | kernel-source | Not affected |
| openSUSE Leap 15.4 | kernel-source-azure | Not affected |
| openSUSE Leap 15.4 | kernel-source-rt | Not affected |
| openSUSE Leap 15.5 | kernel-source | Not affected |
| openSUSE Leap 15.5 | kernel-source-azure | Not affected |
| openSUSE Leap 15.5 | kernel-source-rt | Not affected |
SUSE Timeline for this CVE
CVE page created: Tue Apr 1 20:02:23 2025CVE page last modified: Tue Apr 8 12:23:51 2025