CVE-2022-50851
Unknown Unknown - Not Provided
Use-After-Free Vulnerability in Linux vhost_vdpa Causes Kernel Crash

Publication date: 2025-12-30

Last updated on: 2025-12-30

Assigner: kernel.org

Description
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 ]---
CVSS Scores
EPSS Scores
Probability:
Percentile:
Meta Information
Published
2025-12-30
Last Modified
2025-12-30
Generated
2026-05-07
AI Q&A
2025-12-30
EPSS Evaluated
2026-05-05
NVD
CVE-2022-50851
EUVD
EUVD-2022-55847
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability occurs in the Linux kernel's vhost_vdpa component, where unmapping very large memory regions during vIOMMU testing can cause the kernel to crash. The issue is due to improper handling of large memory unmap requests, which leads to a crash in the Intel IOMMU driver. The fix involves adding a new function, vhost_vdpa_general_unmap(), that only unmaps memory saved in the IOTLB, preventing the crash.


How can this vulnerability impact me? :

This vulnerability can cause the Linux kernel to crash when a guest system attempts to unmap very large memory regions in a virtualized environment using vhost_vdpa and vIOMMU. Such crashes can lead to system instability, downtime, and potential loss of data or service availability.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by monitoring the system logs for kernel crash messages related to vhost_vdpa and iommu unmap operations. Specifically, look for kernel BUG messages and call traces similar to the provided example, which includes lines like 'kernel BUG at drivers/iommu/intel/iommu.c:1174!' and call traces involving vhost_vdpa_unmap and intel_iommu_unmap_pages. You can use commands such as 'dmesg | grep -i vhost_vdpa' or 'journalctl -k | grep -i iommu' to search for relevant kernel error messages indicating the crash.


What immediate steps should I take to mitigate this vulnerability?

The immediate mitigation step is to update the Linux kernel to a version that includes the fix for this vulnerability, which adds the new function vhost_vdpa_general_unmap() to properly handle unmapping large memory regions and prevent crashes. Until the update is applied, monitoring for crash symptoms and avoiding workloads that trigger large memory unmaps in vhost_vdpa may reduce the risk of system crashes.


Ask Our AI Assistant
Need more information? Ask your question to get an AI reply (Powered by our expertise)
0/70
EPSS Chart