CVE-2023-54241
NoneCVSS
—
EPSS
0.2%
Published
Dec 30, 2025
CISA due date
—
Cloudanix analysis
A bug in the Linux kernel on certain MIPS processors can crash the system when trying to start a virtual machine, so systems need an update to prevent unexpected shutdowns.
- Exploitation
- Local Privilege
- Attacker needs
- Local User
- Complexity
- Low
- Impact
- Denial Of Service
- Component
- OS kernel
- Class
- Memory Corruption
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
NULL pointer dereference in kvm_vz_vcpu_setup when vcpu->arch.cop0 is accessed after kvm_mips_commpage_init removal leaves the pointer uninitialized on MIPS VZ KVM guests.
Why it matters to the business
Virtual machine creation fails with kernel crash on affected MIPS systems, causing denial of service for any workloads relying on KVM virtualization and requiring immediate kernel updates.
How an attack unfolds
An attacker with local access invokes KVM guest creation via QEMU or direct ioctls on an unpatched MIPS kernel; the missing cop0 initialization triggers a paging fault during kvm_arch_vcpu_create, crashing the kernel.
How to fix it
Update the Linux kernel to commit cd517f9a9d07d41f4f3593b1da3982261e09d162 or later stable release containing the fix that embeds cop0 instead of using a pointer.
How to confirm the fix worked
Verify the running kernel contains commit cd517f9a9d07d41f4f3593b1da3982261e09d162; attempt KVM guest creation on MIPS VZ hardware and confirm absence of NULL dereference oops.
Typical attack path
- Obtain local execution on MIPS Linux host with KVM enabled
- Launch QEMU or equivalent tool that issues KVM_CREATE_VCPU ioctl
- Trigger kvm_vz_vcpu_setup path that dereferences uninitialized cop0 pointer
- Kernel oops occurs resulting in guest creation failure and potential system instability
How to detect it
Search kernel logs and dmesg for Oops messages referencing kvm_vz_vcpu_setup, NULL pointer at address 0000000000000300, and the call trace involving kvm_arch_vcpu_create and kvm_vm_ioctl.
- kvm_vz_vcpu_setup+0xc4/0x328 [kvm]
- Unable to handle kernel paging request at virtual address 0000000000000300
- kvm_arch_vcpu_create+0x184/0x228 [kvm]
What your security team should do
- Apply the referenced kernel commit immediately on all MIPS systems using KVM
- Disable KVM on MIPS VZ hardware until patched if guest creation is not required
- Monitor kernel logs for the specific oops signature during any virtualization activity
The record
In the Linux kernel, the following vulnerability has been resolved: MIPS: KVM: Fix NULL pointer dereference After commit 45c7e8af4a5e3f0bea4ac209 ("MIPS: Remove KVM_TE support") we get a NULL pointer dereference when creating a KVM guest: [ 146.243409] Starting KVM with MIPS VZ extensions [ 149.849151] CPU 3 Unable to handle kernel paging request at virtual address 0000000000000300, epc == ffffffffc06356ec, ra == ffffffffc063568c [ 149.849177] Oops[#1]: [ 149.849182] CPU: 3 PID: 2265 Comm: qemu-system-mip Not tainted 6.4.0-rc3+ #1671 [ 149.849188] Hardware name: THTF CX TL630 Series/THTF-LS3A4000-7A1000-ML4A, BIOS KL4.1F.TF.D.166.201225.R 12/25/2020 [ 149.849192] $ 0 : 0000000000000000 000000007400cce0 0000000000400004 ffffffff8119c740 [ 149.849209] $ 4 : 000000007400cce1 000000007400cce1 0000000000000000 0000000000000000 [ 149.849221] $ 8 : 000000240058bb36 ffffffff81421ac0 0000000000000000 0000000000400dc0 [ 149.849233] $12 : 9800000102a07cc8 ffffffff80e40e38 0000000000000001 0000000000400dc0 [ 149.849245] $16 : 0000000000000000 9800000106cd0000 9800000106cd0000 9800000100cce000 [ 149.849257] $20 : ffffffffc0632b28 ffffffffc05b31b0 9800000100ccca00 0000000000400000 [ 149.849269] $24 : 9800000106cd09ce ffffffff802f69d0 [ 149.849281] $28 : 9800000102a04000 9800000102a07cd0 98000001106a8000 ffffffffc063568c [ 149.849293] Hi : 00000335b2111e66 [ 149.849295] Lo : 6668d90061ae0ae9 [ 149.849298] epc : ffffffffc06356ec kvm_vz_vcpu_setup+0xc4/0x328 [kvm] [ 149.849324] ra : ffffffffc063568c kvm_vz_vcpu_setup+0x64/0x328 [kvm] [ 149.849336] Status: 7400cce3 KX SX UX KERNEL EXL IE [ 149.849351] Cause : 1000000c (ExcCode 03) [ 149.849354] BadVA : 0000000000000300 [ 149.849357] PrId : 0014c004 (ICT Loongson-3) [ 149.849360] Modules linked in: kvm nfnetlink_queue nfnetlink_log nfnetlink fuse sha256_generic libsha256 cfg80211 rfkill binfmt_misc vfat fat snd_hda_codec_hdmi input_leds led_class snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hda_core snd_pcm snd_timer snd serio_raw xhci_pci radeon drm_suballoc_helper drm_display_helper xhci_hcd ip_tables x_tables [ 149.849432] Process qemu-system-mip (pid: 2265, threadinfo=00000000ae2982d2, task=0000000038e09ad4, tls=000000ffeba16030) [ 149.849439] Stack : 9800000000000003 9800000100ccca00 9800000100ccc000 ffffffffc062cef4 [ 149.849453] 9800000102a07d18 c89b63a7ab338e00 0000000000000000 ffffffff811a0000 [ 149.849465] 0000000000000000 9800000106cd0000 ffffffff80e59938 98000001106a8920 [ 149.849476] ffffffff80e57f30 ffffffffc062854c ffffffff811a0000 9800000102bf4240 [ 149.849488] ffffffffc05b0000 ffffffff80e3a798 000000ff78000000 000000ff78000010 [ 149.849500] 0000000000000255 98000001021f7de0 98000001023f0078 ffffffff81434000 [ 149.849511] 0000000000000000 0000000000000000 9800000102ae0000 980000025e92ae28 [ 149.849523] 0000000000000000 c89b63a7ab338e00 0000000000000001 ffffffff8119dce0 [ 149.849535] 000000ff78000010 ffffffff804f3d3c 9800000102a07eb0 0000000000000255 [ 149.849546] 0000000000000000 ffffffff8049460c 000000ff78000010 0000000000000255 [ 149.849558] ... [ 149.849565] Call Trace: [ 149.849567] [<ffffffffc06356ec>] kvm_vz_vcpu_setup+0xc4/0x328 [kvm] [ 149.849586] [<ffffffffc062cef4>] kvm_arch_vcpu_create+0x184/0x228 [kvm] [ 149.849605] [<ffffffffc062854c>] kvm_vm_ioctl+0x64c/0xf28 [kvm] [ 149.849623] [<ffffffff805209c0>] sys_ioctl+0xc8/0x118 [ 149.849631] [<ffffffff80219eb0>] syscall_common+0x34/0x58 The root cause is the deletion of kvm_mips_commpage_init() leaves vcpu ->arch.cop0 NULL. So fix it by making cop0 from a pointer to an embedded object.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Linux | Kernel | 5.13.0 | 5.15.121 |
| SUSE:Linux Enterprise High Availability Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6_Update_19 | 0 | 1-150600.13.3.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-64kb | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-zfcpdump | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | dtb-aarch64 | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-64kb | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-debug | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| openSUSE:Leap 15.6 | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-kvmsmall | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-obs-qa | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.84.1 |
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