CVE-2022-50636 PCI: Fix pci_device_is_present() for VFs by checking PF
Local attackers with high privileges can cause a denial of service by triggering a hang in virtio I/O operations during driver unbinding or VF removal.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2022-50636?
CVE-2022-50636 is a denial of service vulnerability in Linux, published on 9 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
PCI: Fix pci_device_is_present() for VFs by checking PF
pci_device_is_present() previously didn't work for VFs because it reads the Vendor and Device ID, which are 0xffff for VFs, which looks like they aren't present. Check the PF instead.
Wei Gong reported that if virtio I/O is in progress when the driver is unbound or "0" is written to /sys/.../sriov_numvfs, the virtio I/O operation hangs, which may result in output like this:
task:bash state:D stack: 0 pid: 1773 ppid: 1241 flags:0x00004002 Call Trace: schedule+0x4f/0xc0 blk_mq_freeze_queue_wait+0x69/0xa0 blk_mq_freeze_queue+0x1b/0x20 blk_cleanup_queue+0x3d/0xd0 virtblk_remove+0x3c/0xb0 [virtio_blk] virtio_dev_remove+0x4b/0x80 ... device_unregister+0x1b/0x60 unregister_virtio_device+0x18/0x30 virtio_pci_remove+0x41/0x80 pci_device_remove+0x3e/0xb0
This happened because pci_device_is_present(VF) returned "false" in virtio_pci_remove(), so it called virtio_break_device(). The broken vq meant that vring_interrupt() skipped the vq.callback() that would have completed the virtio I/O operation via virtblk_done().
[bhelgaas: commit log, simplify to always use pci_physfn(), add stable tag]
Which versions are affected by CVE-2022-50636?
How do I fix CVE-2022-50636?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2022-50636 being exploited?
There is no known exploitation of CVE-2022-50636 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2022-50636, GHSA-m8h5-vf45-h85r, UBUNTU-CVE-2022-50636.