Upstream information
Description
In the Linux kernel, the following vulnerability has been resolved:x86/mm: Eliminate window where TLB flushes may be inadvertently skipped
tl;dr: There is a window in the mm switching code where the new CR3 is
set and the CPU should be getting TLB flushes for the new mm. But
should_flush_tlb() has a bug and suppresses the flush. Fix it by
widening the window where should_flush_tlb() sends an IPI.
Long Version:
=== History ===
There were a few things leading up to this.
First, updating mm_cpumask() was observed to be too expensive, so it was
made lazier. But being lazy caused too many unnecessary IPIs to CPUs
due to the now-lazy mm_cpumask(). So code was added to cull
mm_cpumask() periodically[2]. But that culling was a bit too aggressive
and skipped sending TLB flushes to CPUs that need them. So here we are
again.
=== Problem ===
The too-aggressive code in should_flush_tlb() strikes in this window:
// Turn on IPIs for this CPU/mm combination, but only
// if should_flush_tlb() agrees:
cpumask_set_cpu(cpu, mm_cpumask(next));
next_tlb_gen = atomic64_read(&next->context.tlb_gen);
choose_new_asid(next, next_tlb_gen, &new_asid, &need_flush);
load_new_mm_cr3(need_flush);
// ^ After 'need_flush' is set to false, IPIs *MUST*
// be sent to this CPU and not be ignored.
this_cpu_write(cpu_tlbstate.loaded_mm, next);
// ^ Not until this point does should_flush_tlb()
// become true!
should_flush_tlb() will suppress TLB flushes between load_new_mm_cr3()
and writing to 'loaded_mm', which is a window where they should not be
suppressed. Whoops.
=== Solution ===
Thankfully, the fuzzy "just about to write CR3" window is already marked
with loaded_mm==LOADED_MM_SWITCHING. Simply checking for that state in
should_flush_tlb() is sufficient to ensure that the CPU is targeted with
an IPI.
This will cause more TLB flush IPIs. But the window is relatively small
and I do not expect this to cause any kind of measurable performance
impact.
Update the comment where LOADED_MM_SWITCHING is written since it grew
yet another user.
Peter Z also raised a concern that should_flush_tlb() might not observe
'loaded_mm' and 'is_lazy' in the same order that switch_mm_irqs_off()
writes them. Add a barrier to ensure that they are observed in the
order they are written.
SUSE information
Overall state of this security issue: Resolved
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 |
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: 1243520 [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 Desktop 15 SP7 | kernel-default | Not affected |
| SUSE Linux Enterprise Desktop 15 SP7 | kernel-source | Not affected |
| SUSE Linux Enterprise High Availability Extension 15 SP7 | kernel-default | Not affected |
| SUSE Linux Enterprise High Availability Extension 15 SP7 | 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 | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | kernel-default | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | kernel-source-azure | Not 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 Live Patching 15 SP7 | kernel-default | Not affected |
| SUSE Linux Enterprise Live Patching 15 SP7 | kernel-source | Not affected |
| SUSE Linux Enterprise Micro 5.1 | kernel-default | Not affected |
| SUSE Linux Enterprise Micro 5.1 | kernel-rt | Not affected |
| SUSE Linux Enterprise Micro 5.1 | kernel-source | Not affected |
| SUSE Linux Enterprise Micro 5.1 | kernel-source-rt | Not affected |
| SUSE Linux Enterprise Micro 5.2 | kernel-default | Not affected |
| SUSE Linux Enterprise Micro 5.2 | kernel-rt | Not affected |
| SUSE Linux Enterprise Micro 5.2 | kernel-source | Not affected |
| SUSE Linux Enterprise Micro 5.2 | kernel-source-rt | Not 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 Basesystem 15 SP7 | kernel-default | Not affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | 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 Development Tools 15 SP7 | kernel-default | Not affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Legacy 15 SP7 | kernel-default | Not affected |
| SUSE Linux Enterprise Module for Legacy 15 SP7 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Public Cloud 15 SP6 | kernel-source-azure | Not affected |
| SUSE Linux Enterprise Module for Public Cloud 15 SP7 | kernel-source-azure | Not 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 | Not affected |
| SUSE Linux Enterprise Server 15 SP7 | kernel-default | Not affected |
| SUSE Linux Enterprise Server 15 SP7 | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP7 | kernel-source-azure | Not 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 | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | kernel-default | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | kernel-source | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | kernel-source-azure | Not 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 Enterprise Workstation Extension 15 SP7 | kernel-default | Not affected |
| SUSE Linux Enterprise Workstation Extension 15 SP7 | kernel-source | Not affected |
| SUSE Linux Micro 6.0 | kernel-default | Not affected |
| SUSE Linux Micro 6.0 | kernel-source | Not affected |
| SUSE Linux Micro 6.0 | kernel-source-rt | Not affected |
| SUSE Linux Micro 6.1 | kernel-default | Not affected |
| SUSE Linux Micro 6.1 | kernel-source | Not affected |
| SUSE Linux Micro 6.1 | kernel-source-rt | 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 | Not 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 | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-source | Not 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 | Unsupported |
| 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 | Not affected |
| SUSE Linux Enterprise Live Patching 12 SP5 | kernel-source | Not affected |
| SUSE Linux Enterprise Live Patching 15 SP3 | kernel-default | Not affected |
| SUSE Linux Enterprise Live Patching 15 SP3 | kernel-source | Not 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 | Not 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 | Not 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 | Unsupported |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | kernel-default | Not affected |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | kernel-source | Not affected |
| SUSE Linux Enterprise Server 12 SP5 | kernel-source | Not affected |
| SUSE Linux Enterprise Server 12 SP5 | kernel-source-azure | Unsupported |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-source-azure | Unsupported |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | kernel-default | Not affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP3 | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP3-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise Server 15 SP3-LTSS | kernel-source | Not 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 | Unsupported |
| 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 | Not affected |
| SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 | kernel-source-azure | Unsupported |
| SUSE Manager Proxy 4.3 | kernel-default | Not affected |
| SUSE Manager Proxy 4.3 | kernel-source | Not affected |
| SUSE Manager Proxy LTS 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 Retail Branch Server LTS 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 Manager Server LTS 4.3 | kernel-source | Not affected |
| Products past their end of life and not receiving proactive updates anymore. | ||
| SUSE CaaS Platform 4.0 | kernel-source | Not affected |
| SUSE Enterprise Storage 6 | kernel-source | Not affected |
| SUSE Enterprise Storage 7 | kernel-source | Not affected |
| SUSE Enterprise Storage 7.1 | kernel-source | Not affected |
| SUSE Linux Enterprise Desktop 11 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise Desktop 12 SP2 | kernel-source | Not affected |
| SUSE Linux Enterprise Desktop 12 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise Desktop 15 | kernel-source | Not affected |
| SUSE Linux Enterprise Desktop 15 SP1 | kernel-source | Not affected |
| SUSE Linux Enterprise Desktop 15 SP2 | kernel-source | Not affected |
| SUSE Linux Enterprise Desktop 15 SP3 | kernel-source | Not 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 | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1 | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15-ESPOS | kernel-source | Not affected |
| SUSE Linux Enterprise High Performance Computing 15-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Micro 5.0 | kernel-default | Not affected |
| SUSE Linux Enterprise Module for Basesystem 15 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP1 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP2 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Development Tools 15 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP1 | kernel-source | Not affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP2 | kernel-source | Not affected |
| SUSE Linux Enterprise Point of Sale 12 SP2-CLIENT | kernel-source | Not affected |
| SUSE Linux Enterprise Real Time 15 SP2 | kernel-source | Not affected |
| SUSE Linux Enterprise Real Time 15 SP3 | kernel-source | Not affected |
| SUSE Linux Enterprise Real Time 15 SP3 | kernel-source-rt | Not 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 | Not affected |
| SUSE Linux Enterprise Server 11 SP4 LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise Server 11 SP4 LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Server 11 SP4-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Server 12 SP2 | kernel-source | Not affected |
| SUSE Linux Enterprise Server 12 SP2-BCL | kernel-source | Not affected |
| SUSE Linux Enterprise Server 12 SP2-ESPOS | kernel-source | Not affected |
| SUSE Linux Enterprise Server 12 SP2-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise Server 12 SP2-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Server 12 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise Server 12 SP4-ESPOS | kernel-source | Not affected |
| SUSE Linux Enterprise Server 12 SP4-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise Server 12 SP4-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP1 | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP1-BCL | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP1-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise Server 15 SP1-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP2 | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP2-BCL | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP2-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise Server 15 SP2-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15 SP3-BCL | kernel-source | Not affected |
| SUSE Linux Enterprise Server 15-LTSS | kernel-default | Not affected |
| SUSE Linux Enterprise Server 15-LTSS | kernel-source | Not affected |
| SUSE Linux Enterprise Server for Raspberry Pi 12 SP2 | kernel-source | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP2 | kernel-source | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP4 | kernel-source | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 | kernel-source | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP1 | kernel-source | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | kernel-source | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | kernel-source | 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-source | Not affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | kernel-source-azure | Unsupported |
| SUSE Manager Proxy 4.0 | kernel-source | Not affected |
| SUSE Manager Proxy 4.1 | kernel-source | Not affected |
| SUSE Manager Proxy 4.2 | kernel-source | Not affected |
| SUSE Manager Retail Branch Server 4.0 | kernel-source | Not affected |
| SUSE Manager Retail Branch Server 4.1 | kernel-source | Not affected |
| SUSE Manager Retail Branch Server 4.2 | kernel-source | Not affected |
| SUSE Manager Server 4.0 | kernel-source | Not affected |
| SUSE Manager Server 4.1 | kernel-source | Not affected |
| SUSE Manager Server 4.2 | kernel-source | Not affected |
| SUSE OpenStack Cloud 7 | kernel-source | Not affected |
| SUSE OpenStack Cloud 9 | kernel-source | Not affected |
| SUSE OpenStack Cloud Crowbar 9 | kernel-source | Not affected |
| SUSE Real Time Module 15 SP3 | kernel-source-rt | Not 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 | Not affected |
| openSUSE Leap 15.3 | kernel-source-rt | Not affected |
| openSUSE Leap 15.4 | kernel-source | Not affected |
| openSUSE Leap 15.4 | kernel-source-azure | Unsupported |
| openSUSE Leap 15.4 | kernel-source-rt | Not affected |
| openSUSE Leap 15.5 | kernel-source | Not affected |
| openSUSE Leap 15.5 | kernel-source-azure | Unsupported |
| openSUSE Leap 15.5 | kernel-source-rt | Not affected |
SUSE Timeline for this CVE
CVE page created: Tue May 20 20:01:08 2025CVE page last modified: Tue Jul 1 17:03:48 2025