PCI/IOV: Fix race between SR-IOV enable/disable and hotplug

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: PCI/IOV: Fix race between SR-IOV enable/disable and hotplug Commit 05703271c3cd ("PCI/IOV: Add PCI rescan-remove locking when enabling/disabling SR-IOV") tried to fix a race between the VF removal inside sriov_del_vfs() and concurrent hot unplug by taking the PCI rescan/remove lock in sriov_del_vfs(). Similarly the PCI rescan/remove lock was also taken in sriov_add_vfs() to protect addition of VFs. This approach however causes deadlock on trying to remove PFs with SR-IOV enabled because PFs disable SR-IOV during removal and this removal happens under the PCI rescan/remove lock. So the original fix had to be reverted. Instead of taking the PCI rescan/remove lock in sriov_add_vfs() and sriov_del_vfs(), fix the race that occurs with SR-IOV enable and disable vs hotplug higher up in the callchain by taking the lock in sriov_numvfs_store() before calling into the driver's sriov_configure() callback.

References

• https://git.kernel.org/stable/c/3cddde484471c602bea04e6f384819d336a1ff84
• https://git.kernel.org/stable/c/d7673ac466eca37ec3e6b7cc9ccdb06de3304e9b
• https://git.kernel.org/stable/c/7c37920c96b85ef4255a7acc795e99e63dd38d59
• https://git.kernel.org/stable/c/1047ca2d816994f31e1475e63e0c0b7825599747
• https://git.kernel.org/stable/c/97c18f074ff1c12d016a0753072a3afdfa0b9611
• https://git.kernel.org/stable/c/bea1d373098b22d7142da48750ce5526096425bc
• https://git.kernel.org/stable/c/f3015627b6e9ddf85cfeaf42405b3c194dde2c36
• https://git.kernel.org/stable/c/a5338e365c4559d7b4d7356116b0eb95b12e08d5