CVE-2025-40184: KVM: arm64: Fix debug checking for np-guests using huge mappings
In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Fix debug checking for np-guests using huge mappings
When running with transparent huge pages and CONFIGNVHEEL2DEBUG then the debug checking in asserthostsharedguest() fails on the launch of an np-guest. This WARNON() causes a panic and generates the stack below.
In pkvmhostrelaxpermsguest() the debug checking assumes the mapping is a single page but it may be a block map. Update the checking so that the size is not checked and just assumes the correct size.
While we're here make the same fix in pkvmhostmkyoungguest().
Info: # lkvm run -k /share/arch/arm64/boot/Image -m 704 -c 8 --name guest-128 Info: Removed ghost socket file "/.lkvm//guest-128.sock". [ 1406.521757] kvm [141]: nVHE hyp BUG at: arch/arm64/kvm/hyp/nvhe/memprotect.c:1088! [ 1406.521804] kvm [141]: nVHE call trace: [ 1406.521828] kvm [141]: [<ffff8000811676b4>] kvmnvhehyppanic+0xb4/0xe8 [ 1406.521946] kvm [141]: [<ffff80008116d12c>] kvmnvheasserthostsharedguest+0xb0/0x10c [ 1406.522049] kvm [141]: [<ffff80008116f068>] kvmnvhepkvmhostrelaxpermsguest+0x48/0x104 [ 1406.522157] kvm [141]: [<ffff800081169df8>] kvmnvhehandlepkvmhostrelaxpermsguest+0x64/0x7c [ 1406.522250] kvm [141]: [<ffff800081169f0c>] kvmnvhehandletrap+0x8c/0x1a8 [ 1406.522333] kvm [141]: [<ffff8000811680fc>] kvmnvheskippauthsave+0x4/0x4 [ 1406.522454] kvm [141]: ---[ end nVHE call trace ]--- [ 1406.522477] kvm [141]: Hyp Offset: 0xfffece8013600000 [ 1406.522554] Kernel panic - not syncing: HYP panic: [ 1406.522554] PS:834003c9 PC:0000b1806db6d170 ESR:00000000f2000800 [ 1406.522554] FAR:ffff8000804be420 HPFAR:0000000000804be0 PAR:0000000000000000 [ 1406.522554] VCPU:0000000000000000 [ 1406.523337] CPU: 3 UID: 0 PID: 141 Comm: kvm-vcpu-0 Not tainted 6.16.0-rc7 #97 PREEMPT [ 1406.523485] Hardware name: FVP Base RevC (DT) [ 1406.523566] Call trace: [ 1406.523629] showstack+0x18/0x24 (C) [ 1406.523753] dumpstacklvl+0xd4/0x108 [ 1406.523899] dumpstack+0x18/0x24 [ 1406.524040] panic+0x3d8/0x448 [ 1406.524184] nvhehyppanichandler+0x10c/0x23c [ 1406.524325] kvmhandleguestabort+0x68c/0x109c [ 1406.524500] handleexit+0x60/0x17c [ 1406.524630] kvmarchvcpuioctlrun+0x2e0/0x8c0 [ 1406.524794] kvmvcpuioctl+0x1a8/0x9cc [ 1406.524919] arm64sysioctl+0xac/0x104 [ 1406.525067] invokesyscall+0x48/0x10c [ 1406.525189] el0svccommon.constprop.0+0x40/0xe0 [ 1406.525322] doel0svc+0x1c/0x28 [ 1406.525441] el0svc+0x38/0x120 [ 1406.525588] el0t64synchandler+0x10c/0x138 [ 1406.525750] el0t64sync+0x1ac/0x1b0 [ 1406.525876] SMP: stopping secondary CPUs [ 1406.525965] Kernel Offset: disabled [ 1406.526032] CPU features: 0x0000,00000080,8e134ca1,9446773f [ 1406.526130] Memory Limit: none [ 1406.959099] ---[ end Kernel panic - not syncing: HYP panic: [ 1406.959099] PS:834003c9 PC:0000b1806db6d170 ESR:00000000f2000800 [ 1406.959099] FAR:ffff8000804be420 HPFAR:0000000000804be0 PAR:0000000000000000 [ 1406.959099] VCPU:0000000000000000 ]
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2025-40184?
CVE-2025-40184 is classified as a medium severity vulnerability in the Linux kernel.
How do I fix CVE-2025-40184?
To fix CVE-2025-40184, you should update your Linux kernel to the latest patched version provided by your distribution.
What does CVE-2025-40184 affect?
CVE-2025-40184 affects the Linux kernel when running with transparent huge pages and specific debug configurations.
What are the consequences of CVE-2025-40184?
The consequences of CVE-2025-40184 may include failures in debug checks during the launch of non-persistent guests.
Is CVE-2025-40184 exploitable?
While CVE-2025-40184 does not present an exploitable condition, it can lead to debugging errors in specific configurations.