CVE-2022-49434 PCI: Avoid pci_dev_lock() AB/BA deadlock with sriov_numvfs_store()
A deadlock in the Linux kernel PCI subsystem can cause a denial of service when specific SR-IOV and reset operations occur concurrently.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2022-49434?
CVE-2022-49434 is a medium-severity vulnerability in Linux kernel, published on 26 Feb 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: Avoid pci_dev_lock() AB/BA deadlock with sriov_numvfs_store()
The sysfs sriov_numvfs_store() path acquires the device lock before the config space access lock:
sriov_numvfs_store device_lock # A (1) acquire device lock sriov_configure vfio_pci_sriov_configure # (for example) vfio_pci_core_sriov_configure pci_disable_sriov sriov_disable pci_cfg_access_lock pci_wait_cfg # B (4) wait for dev->block_cfg_access == 0
Previously, pci_dev_lock() acquired the config space access lock before the device lock:
pci_dev_lock pci_cfg_access_lock dev->block_cfg_access = 1 # B (2) set dev->block_cfg_access = 1 device_lock # A (3) wait for device lock
Any path that uses pci_dev_lock(), e.g., pci_reset_function(), may deadlock with sriov_numvfs_store() if the operations occur in the sequence (1) (2) (3) (4).
Avoid the deadlock by reversing the order in pci_dev_lock() so it acquires the device lock before the config space access lock, the same as the sriov_numvfs_store() path.
[bhelgaas: combined and adapted commit log from Jay Zhou's independent subsequent posting: https://lore.kernel.org/r/[email protected]]
Weakness: CWE-667
Which versions are affected by CVE-2022-49434?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-49434?
Apply the vendor's patch.
Is CVE-2022-49434 being exploited?
There is no known exploitation of CVE-2022-49434 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-49434, GHSA-fxw3-5jmj-82p9, UBUNTU-CVE-2022-49434.