linux/arch/s390/pci
Niklas Schnelle ab90950985 PCI: s390: Fix use-after-free of PCI resources with per-function hotplug
On s390 PCI functions may be hotplugged individually even when they
belong to a multi-function device. In particular on an SR-IOV device VFs
may be removed and later re-added.

In commit a50297cf82 ("s390/pci: separate zbus creation from
scanning") it was missed however that struct pci_bus and struct
zpci_bus's resource list retained a reference to the PCI functions MMIO
resources even though those resources are released and freed on
hot-unplug. These stale resources may subsequently be claimed when the
PCI function re-appears resulting in use-after-free.

One idea of fixing this use-after-free in s390 specific code that was
investigated was to simply keep resources around from the moment a PCI
function first appeared until the whole virtual PCI bus created for
a multi-function device disappears. The problem with this however is
that due to the requirement of artificial MMIO addreesses (address
cookies) extra logic is then needed to keep the address cookies
compatible on re-plug. At the same time the MMIO resources semantically
belong to the PCI function so tying their lifecycle to the function
seems more logical.

Instead a simpler approach is to remove the resources of an individually
hot-unplugged PCI function from the PCI bus's resource list while
keeping the resources of other PCI functions on the PCI bus untouched.

This is done by introducing pci_bus_remove_resource() to remove an
individual resource. Similarly the resource also needs to be removed
from the struct zpci_bus's resource list. It turns out however, that
there is really no need to add the MMIO resources to the struct
zpci_bus's resource list at all and instead we can simply use the
zpci_bar_struct's resource pointer directly.

Fixes: a50297cf82 ("s390/pci: separate zbus creation from scanning")
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20230306151014.60913-2-schnelle@linux.ibm.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2023-03-13 09:15:11 +01:00
..
Makefile KVM: s390: pci: Hook to access KVM lowlevel from VFIO 2022-08-29 13:29:28 +02:00
pci_bus.c PCI: s390: Fix use-after-free of PCI resources with per-function hotplug 2023-03-13 09:15:11 +01:00
pci_bus.h PCI: s390: Fix use-after-free of PCI resources with per-function hotplug 2023-03-13 09:15:11 +01:00
pci_clp.c s390/pci: stash dtsm and maxstbl 2022-07-11 09:54:24 +02:00
pci_debug.c s390/pci: make better use of zpci_dbg() levels 2022-04-25 13:54:15 +02:00
pci_dma.c iommu/s390: Use GFP_KERNEL in sleepable contexts 2023-01-25 11:52:07 +01:00
pci_event.c s390/pci: don't log availability events as errors 2022-04-25 13:54:15 +02:00
pci_insn.c KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding 2022-07-11 09:54:32 +02:00
pci_iov.c s390/pci: add missing pci_iov.h include 2020-09-16 14:08:47 +02:00
pci_iov.h s390/pci: consolidate SR-IOV specific code 2020-09-14 11:38:34 +02:00
pci_irq.c s390/pci: Use irq_data_get_msi_desc() 2022-11-23 16:22:21 +01:00
pci_kvm_hook.c KVM: s390: pci: Hook to access KVM lowlevel from VFIO 2022-08-29 13:29:28 +02:00
pci_mmio.c s390/pci: add missing EX_TABLE entries to __pcistg_mio_inuser()/__pcilg_mio_inuser() 2022-10-26 14:47:31 +02:00
pci_sysfs.c s390/pci: tolerate inconsistent handle in recover 2021-10-04 09:49:36 +02:00
pci.c PCI: s390: Fix use-after-free of PCI resources with per-function hotplug 2023-03-13 09:15:11 +01:00