Upstream information

CVE-2025-40040 at MITRE

Description

In the Linux kernel, the following vulnerability has been resolved:

mm/ksm: fix flag-dropping behavior in ksm_madvise

syzkaller discovered the following crash: (kernel BUG)

[ 44.607039] ------------[ cut here ]------------
[ 44.607422] kernel BUG at mm/userfaultfd.c:2067!
[ 44.608148] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI
[ 44.608814] CPU: 1 UID: 0 PID: 2475 Comm: reproducer Not tainted 6.16.0-rc6 #1 PREEMPT(none)
[ 44.609635] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 44.610695] RIP: 0010:userfaultfd_release_all+0x3a8/0x460

<snip other registers, drop unreliable trace>

[ 44.617726] Call Trace:
[ 44.617926] <TASK>
[ 44.619284] userfaultfd_release+0xef/0x1b0
[ 44.620976] __fput+0x3f9/0xb60
[ 44.621240] fput_close_sync+0x110/0x210
[ 44.622222] __x64_sys_close+0x8f/0x120
[ 44.622530] do_syscall_64+0x5b/0x2f0
[ 44.622840] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 44.623244] RIP: 0033:0x7f365bb3f227

Kernel panics because it detects UFFD inconsistency during
userfaultfd_release_all(). Specifically, a VMA which has a valid pointer
to vma->vm_userfaultfd_ctx, but no UFFD flags in vma->vm_flags.

The inconsistency is caused in ksm_madvise(): when user calls madvise()
with MADV_UNMEARGEABLE on a VMA that is registered for UFFD in MINOR mode,
it accidentally clears all flags stored in the upper 32 bits of
vma->vm_flags.

Assuming x86_64 kernel build, unsigned long is 64-bit and unsigned int and
int are 32-bit wide. This setup causes the following mishap during the &=
~VM_MERGEABLE assignment.

VM_MERGEABLE is a 32-bit constant of type unsigned int, 0x8000'0000.
After ~ is applied, it becomes 0x7fff'ffff unsigned int, which is then
promoted to unsigned long before the & operation. This promotion fills
upper 32 bits with leading 0s, as we're doing unsigned conversion (and
even for a signed conversion, this wouldn't help as the leading bit is 0).
& operation thus ends up AND-ing vm_flags with 0x0000'0000'7fff'ffff
instead of intended 0xffff'ffff'7fff'ffff and hence accidentally clears
the upper 32-bits of its value.

Fix it by changing `VM_MERGEABLE` constant to unsigned long, using the
BIT() macro.

Note: other VM_* flags are not affected: This only happens to the
VM_MERGEABLE flag, as the other VM_* flags are all constants of type int
and after ~ operation, they end up with leading 1 and are thus converted
to unsigned long with leading 1s.

Note 2:
After commit 31defc3b01d9 ("userfaultfd: remove (VM_)BUG_ON()s"), this is
no longer a kernel BUG, but a WARNING at the same place:

[ 45.595973] WARNING: CPU: 1 PID: 2474 at mm/userfaultfd.c:2067

but the root-cause (flag-drop) remains the same.

[akpm@linux-foundation.org: rust bindgen wasn't able to handle BIT(), from Miguel]

SUSE information

Overall state of this security issue: Pending

This issue is currently rated as having moderate severity.

CVSS v3 Scores
CVSS detail 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
CVSS v4 Scores
CVSS detail SUSE
Base Score 6.8
Vector CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Attack Vector Local
Attack Complexity Low
Attack Requirements None
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: 1252780 [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 Affected
SUSE Linux Enterprise Desktop 15 SP6 kernel-source Affected
SUSE Linux Enterprise Desktop 15 SP7 kernel-default Affected
SUSE Linux Enterprise Desktop 15 SP7 kernel-source Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 kernel-default Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 kernel-source Affected
SUSE Linux Enterprise High Performance Computing 15 SP6 kernel-default Affected
SUSE Linux Enterprise High Performance Computing 15 SP6 kernel-source Affected
SUSE Linux Enterprise High Performance Computing 15 SP6 kernel-source-azure Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 kernel-default Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 kernel-source Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 kernel-source-azure Affected
SUSE Linux Enterprise Live Patching 15 SP6 kernel-default Affected
SUSE Linux Enterprise Live Patching 15 SP6 kernel-source Affected
SUSE Linux Enterprise Live Patching 15 SP7 kernel-default Affected
SUSE Linux Enterprise Live Patching 15 SP7 kernel-source 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 Affected
SUSE Linux Enterprise Micro 5.3 kernel-rt Affected
SUSE Linux Enterprise Micro 5.3 kernel-source Affected
SUSE Linux Enterprise Micro 5.3 kernel-source-rt Affected
SUSE Linux Enterprise Micro 5.4 kernel-default Affected
SUSE Linux Enterprise Micro 5.4 kernel-rt Affected
SUSE Linux Enterprise Micro 5.4 kernel-source Affected
SUSE Linux Enterprise Micro 5.4 kernel-source-rt Affected
SUSE Linux Enterprise Micro 5.5 kernel-default Affected
SUSE Linux Enterprise Micro 5.5 kernel-source Affected
SUSE Linux Enterprise Micro 5.5 kernel-source-rt Affected
SUSE Linux Enterprise Module for Basesystem 15 SP6 kernel-default Affected
SUSE Linux Enterprise Module for Basesystem 15 SP6 kernel-source Affected
SUSE Linux Enterprise Module for Basesystem 15 SP7 kernel-default Affected
SUSE Linux Enterprise Module for Basesystem 15 SP7 kernel-source Affected
SUSE Linux Enterprise Module for Development Tools 15 SP6 kernel-default Affected
SUSE Linux Enterprise Module for Development Tools 15 SP6 kernel-source Affected
SUSE Linux Enterprise Module for Development Tools 15 SP7 kernel-default Affected
SUSE Linux Enterprise Module for Development Tools 15 SP7 kernel-source Affected
SUSE Linux Enterprise Module for Legacy 15 SP6 kernel-default Affected
SUSE Linux Enterprise Module for Legacy 15 SP6 kernel-source Affected
SUSE Linux Enterprise Module for Legacy 15 SP7 kernel-default Affected
SUSE Linux Enterprise Module for Legacy 15 SP7 kernel-source Affected
SUSE Linux Enterprise Module for Public Cloud 15 SP6 kernel-source-azure Affected
SUSE Linux Enterprise Module for Public Cloud 15 SP7 kernel-source-azure Affected
SUSE Linux Enterprise Real Time 15 SP6 kernel-source-rt Affected
SUSE Linux Enterprise Real Time 15 SP7 kernel-source-rt Affected
SUSE Linux Enterprise Server 15 SP6 kernel-default Affected
SUSE Linux Enterprise Server 15 SP6 kernel-source Affected
SUSE Linux Enterprise Server 15 SP6 kernel-source-azure Affected
SUSE Linux Enterprise Server 15 SP7 kernel-default Affected
SUSE Linux Enterprise Server 15 SP7 kernel-source Affected
SUSE Linux Enterprise Server 15 SP7 kernel-source-azure Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP6 kernel-default Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP6 kernel-source Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP6 kernel-source-azure Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP7 kernel-default Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP7 kernel-source Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP7 kernel-source-azure Affected
SUSE Linux Enterprise Workstation Extension 15 SP6 kernel-default Affected
SUSE Linux Enterprise Workstation Extension 15 SP6 kernel-source Affected
SUSE Linux Enterprise Workstation Extension 15 SP7 kernel-default Affected
SUSE Linux Enterprise Workstation Extension 15 SP7 kernel-source 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 Real Time Module 15 SP6 kernel-source-rt Affected
SUSE Real Time Module 15 SP7 kernel-source-rt Affected
openSUSE Leap 15.6 kernel-default Affected
openSUSE Leap 15.6 kernel-source Affected
openSUSE Leap 15.6 kernel-source-azure Affected
openSUSE Leap 15.6 kernel-source-rt 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 Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS kernel-default Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS kernel-source Affected
SUSE Linux Enterprise High Performance Computing 15 SP5 kernel-source Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS kernel-default Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS kernel-source Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS kernel-default Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS kernel-source 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 Affected
SUSE Linux Enterprise Live Patching 15 SP4 kernel-source Affected
SUSE Linux Enterprise Live Patching 15 SP5 kernel-default Affected
SUSE Linux Enterprise Live Patching 15 SP5 kernel-source Affected
SUSE Linux Enterprise Module for Basesystem 15 SP3 kernel-source Not affected
SUSE Linux Enterprise Module for Basesystem 15 SP4 kernel-source Affected
SUSE Linux Enterprise Module for Basesystem 15 SP5 kernel-source 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 Affected
SUSE Linux Enterprise Module for Development Tools 15 SP5 kernel-source Affected
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-LTSS kernel-default Not affected
SUSE Linux Enterprise Server 12 SP5-LTSS kernel-source Not affected
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 Affected
SUSE Linux Enterprise Server 15 SP4-LTSS kernel-default Affected
SUSE Linux Enterprise Server 15 SP4-LTSS kernel-source Affected
SUSE Linux Enterprise Server 15 SP5 kernel-source Affected
SUSE Linux Enterprise Server 15 SP5-LTSS kernel-default Affected
SUSE Linux Enterprise Server 15 SP5-LTSS kernel-source Affected
SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 kernel-source Not affected
SUSE Manager Proxy 4.3 kernel-source Affected
SUSE Manager Proxy LTS 4.3 kernel-default Affected
SUSE Manager Proxy LTS 4.3 kernel-source Affected
SUSE Manager Retail Branch Server 4.3 kernel-source Affected
SUSE Manager Retail Branch Server LTS 4.3 kernel-default Affected
SUSE Manager Retail Branch Server LTS 4.3 kernel-source Affected
SUSE Manager Server 4.3 kernel-source Affected
SUSE Manager Server LTS 4.3 kernel-default Affected
SUSE Manager Server LTS 4.3 kernel-source 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 Affected
SUSE Linux Enterprise Desktop 15 SP5 kernel-source 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 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 Affected
SUSE Linux Enterprise Real Time 15 SP4 kernel-source-rt Affected
SUSE Linux Enterprise Real Time 15 SP5 kernel-source-rt 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-default 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-default Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP4 kernel-source Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP5 kernel-default Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP5 kernel-source Affected
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 Affected
SUSE Real Time Module 15 SP5 kernel-source-rt Affected
openSUSE Leap 15.3 kernel-source Not affected
openSUSE Leap 15.3 kernel-source-rt Not affected
openSUSE Leap 15.4 kernel-source Affected
openSUSE Leap 15.4 kernel-source-rt Affected
openSUSE Leap 15.5 kernel-source Affected
openSUSE Leap 15.5 kernel-source-rt Affected


SUSE Timeline for this CVE

CVE page created: Tue Oct 28 14:02:23 2025
CVE page last modified: Wed Oct 29 16:35:38 2025