CVE-2022-49434: PCI: Avoid pci_dev_lock() AB/BA deadlock with sriov_numvfs_store()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

The Linux kernel CVE team has assigned CVE-2022-49434 to this issue.


Affected and fixed versions
===========================

	Fixed in 4.9.318 with commit da9792920ab525b8a932aa9aeee34529ad7b83f7
	Fixed in 4.14.283 with commit c3c6dc1853b8bf3c718f96fd8480a6eb09ba4831
	Fixed in 4.19.247 with commit aed6d4d519210c28817948f34c53b6e058e0456c
	Fixed in 5.4.198 with commit c9a81f9ed6ae3554621d6a50220b1bc74b67d81e
	Fixed in 5.10.121 with commit eff3587b9c01439b738298475e555c028ac9f55e
	Fixed in 5.15.46 with commit 2cdd5284035322795b0964f899eefba254cfe483
	Fixed in 5.17.14 with commit ea047f51172aa68841adef7f52d375002438b8f0
	Fixed in 5.18.3 with commit 59ea6b3ae51df7cd6bfd84c9c0030609b9315622
	Fixed in 5.19 with commit a91ee0e9fca9d7501286cfbced9b30a33e52740a

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-49434
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/pci/pci.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/da9792920ab525b8a932aa9aeee34529ad7b83f7
	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