CVE-2022-50851
NoneCVSS
—
EPSS
0.2%
Published
Dec 30, 2025
CISA due date
—
Cloudanix analysis
A bug in the Linux kernel can make virtual machines crash the entire host computer when they try to free large amounts of memory, and updating the kernel fixes it.
- Exploitation
- Local Privilege
- Attacker needs
- Low Privilege
- Complexity
- Moderate
- Impact
- Denial Of Service
- Component
- OS kernel
- Class
- Memory Corruption
- Remediation
- Patch
- Effort
- Low
- Patch risk
- Low
What it actually does
The flaw allows a guest to trigger a kernel BUG during IOMMU unmap of very large memory regions in vhost_vdpa because vhost_vdpa_unmap did not restrict unmaps to only entries present in the iotlb, leading to invalid domain_unmap calls.
Why it matters to the business
Systems running affected Linux kernels with vhost_vdpa and vIOMMU can experience sudden kernel crashes and reboots when guests perform large memory unmaps, disrupting virtual machine operation and requiring restarts.
How an attack unfolds
An attacker controlling a guest VM sends an IOTLB message requesting unmap of a very large memory region; the vhost_vdpa code path calls into the IOMMU unmap routine without validating against saved iotlb entries, hitting the domain_unmap assertion and crashing the host kernel.
How to fix it
Upgrade to a fixed kernel containing commit 26b7400c89b81e2f6de4f224ba1fdf06f293de31 or apply the Debian package updates (linux 4.11.11-1 or later) that introduce vhost_vdpa_general_unmap to restrict unmaps to iotlb-tracked memory only.
How to confirm the fix worked
Confirm the running kernel contains the fix commit or package version, then test vIOMMU guest unmap operations of large regions to ensure no BUG or panic occurs in domain_unmap.
Typical attack path
- Attacker gains control of a guest VM using vhost_vdpa with vIOMMU enabled
- Guest issues large memory unmap request via IOTLB message
- vhost_vdpa_process_iotlb_msg calls vhost_vdpa_unmap without iotlb filtering
- intel_iommu_unmap_pages invokes domain_unmap on invalid range
- Kernel hits BUG at domain_unmap and panics
How to detect it
Search kernel logs and crash dumps for the exact BUG signature at domain_unmap+0x48 combined with the call trace through vhost_vdpa_unmap and vhost_vdpa_process_iotlb_msg; absence of such oops after large unmap activity indicates the issue was not triggered.
What your security team should do
- Prioritize patching hosts using vhost_vdpa with vIOMMU to the fixed versions immediately due to crash risk in production VMs
- Monitor for kernel oops logs matching the domain_unmap BUG signature until patches are deployed
- Review virtualization configurations to limit exposure of vhost_vdpa devices to untrusted guests
The record
In the Linux kernel, the following vulnerability has been resolved: vhost_vdpa: fix the crash in unmap a large memory While testing in vIOMMU, sometimes Guest will unmap very large memory, which will cause the crash. To fix this, add a new function vhost_vdpa_general_unmap(). This function will only unmap the memory that saved in iotlb. Call Trace: [ 647.820144] ------------[ cut here ]------------ [ 647.820848] kernel BUG at drivers/iommu/intel/iommu.c:1174! [ 647.821486] invalid opcode: 0000 [#1] PREEMPT SMP PTI [ 647.822082] CPU: 10 PID: 1181 Comm: qemu-system-x86 Not tainted 6.0.0-rc1home_lulu_2452_lulu7_vhost+ #62 [ 647.823139] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.15.0-29-g6a62e0cb0dfe-prebuilt.qem4 [ 647.824365] RIP: 0010:domain_unmap+0x48/0x110 [ 647.825424] Code: 48 89 fb 8d 4c f6 1e 39 c1 0f 4f c8 83 e9 0c 83 f9 3f 7f 18 48 89 e8 48 d3 e8 48 85 c0 75 59 [ 647.828064] RSP: 0018:ffffae5340c0bbf0 EFLAGS: 00010202 [ 647.828973] RAX: 0000000000000001 RBX: ffff921793d10540 RCX: 000000000000001b [ 647.830083] RDX: 00000000080000ff RSI: 0000000000000001 RDI: ffff921793d10540 [ 647.831214] RBP: 0000000007fc0100 R08: ffffae5340c0bcd0 R09: 0000000000000003 [ 647.832388] R10: 0000007fc0100000 R11: 0000000000100000 R12: 00000000080000ff [ 647.833668] R13: ffffae5340c0bcd0 R14: ffff921793d10590 R15: 0000008000100000 [ 647.834782] FS: 00007f772ec90640(0000) GS:ffff921ce7a80000(0000) knlGS:0000000000000000 [ 647.836004] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 647.836990] CR2: 00007f02c27a3a20 CR3: 0000000101b0c006 CR4: 0000000000372ee0 [ 647.838107] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 647.839283] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 647.840666] Call Trace: [ 647.841437] <TASK> [ 647.842107] intel_iommu_unmap_pages+0x93/0x140 [ 647.843112] __iommu_unmap+0x91/0x1b0 [ 647.844003] iommu_unmap+0x6a/0x95 [ 647.844885] vhost_vdpa_unmap+0x1de/0x1f0 [vhost_vdpa] [ 647.845985] vhost_vdpa_process_iotlb_msg+0xf0/0x90b [vhost_vdpa] [ 647.847235] ? _raw_spin_unlock+0x15/0x30 [ 647.848181] ? _copy_from_iter+0x8c/0x580 [ 647.849137] vhost_chr_write_iter+0xb3/0x430 [vhost] [ 647.850126] vfs_write+0x1e4/0x3a0 [ 647.850897] ksys_write+0x53/0xd0 [ 647.851688] do_syscall_64+0x3a/0x90 [ 647.852508] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 647.853457] RIP: 0033:0x7f7734ef9f4f [ 647.854408] Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 29 76 f8 ff 48 8b 54 24 18 48 8b 74 24 10 41 89 c8 [ 647.857217] RSP: 002b:00007f772ec8f040 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 [ 647.858486] RAX: ffffffffffffffda RBX: 00000000fef00000 RCX: 00007f7734ef9f4f [ 647.859713] RDX: 0000000000000048 RSI: 00007f772ec8f090 RDI: 0000000000000010 [ 647.860942] RBP: 00007f772ec8f1a0 R08: 0000000000000000 R09: 0000000000000000 [ 647.862206] R10: 0000000000000001 R11: 0000000000000293 R12: 0000000000000010 [ 647.863446] R13: 0000000000000002 R14: 0000000000000000 R15: ffffffff01100000 [ 647.864692] </TASK> [ 647.865458] Modules linked in: rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache netfs v] [ 647.874688] ---[ end trace 0000000000000000 ]---
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Linux | Kernel | 5.7.0 | 6.0.19 |
| SUSE:Linux Enterprise High Availability Extension 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Live Patching 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Live Patching 15 SP4 | kernel-livepatch-SLE15-SP4_Update_48 | 0 | 1-150400.9.7.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-source-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-source-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-rt | 0 | 5.14.21-150500.13.118.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-source-rt | 0 | 5.14.21-150500.13.118.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-zfcpdump | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
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