CVE-2022-49434

Summary

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/20220404062539.1710-1-jianjay.zhou@huawei.com]

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/c3c6dc1853b8bf3c718f96fd8480a6eb09ba4831
• https://git.kernel.org/stable/c/aed6d4d519210c28817948f34c53b6e058e0456c
• https://git.kernel.org/stable/c/c9a81f9ed6ae3554621d6a50220b1bc74b67d81e
• https://git.kernel.org/stable/c/eff3587b9c01439b738298475e555c028ac9f55e
• https://git.kernel.org/stable/c/2cdd5284035322795b0964f899eefba254cfe483
• https://git.kernel.org/stable/c/ea047f51172aa68841adef7f52d375002438b8f0
• https://git.kernel.org/stable/c/59ea6b3ae51df7cd6bfd84c9c0030609b9315622
• https://git.kernel.org/stable/c/a91ee0e9fca9d7501286cfbced9b30a33e52740a

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