linux/drivers/pci/pcie
Yinghai Lu 3bd7db63a8 PCI/ASPM: Always set link->downstream to avoid NULL dereference on remove
We call pcie_aspm_exit_link_state() when we remove a device.  If the device
is the last PCIe function to be removed below a bridge and the bridge has
an ASPM link_state struct, we disable ASPM on the link.  Disabling ASPM
requires link->downstream (used in pcie_config_aspm_link()).

We previously set link->downstream in pcie_aspm_cap_init(), but only if the
device was not blacklisted.  Removing the blacklisted device caused a NULL
pointer dereference in the pcie_aspm_exit_link_state() ->
pcie_config_aspm_link() path:

  # echo 1 > /sys/bus/pci/devices/0000\:0b\:00.0/remove
  ...
   BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
   IP: pcie_config_aspm_link+0x5d/0x2b0
   Call Trace:
    pcie_aspm_exit_link_state+0x75/0x130
    pci_stop_bus_device+0xa4/0xb0
    pci_stop_and_remove_bus_device_locked+0x1a/0x30
    remove_store+0x50/0x70
    dev_attr_store+0x18/0x30
    sysfs_kf_write+0x44/0x60
    kernfs_fop_write+0x10e/0x190
    __vfs_write+0x28/0x110
    ? rcu_read_lock_sched_held+0x5d/0x80
    ? rcu_sync_lockdep_assert+0x2c/0x60
    ? __sb_start_write+0x173/0x1a0
    ? vfs_write+0xb3/0x180
    vfs_write+0xc4/0x180
    SyS_write+0x49/0xa0
    do_syscall_64+0xa6/0x1c0
    entry_SYSCALL64_slow_path+0x25/0x25
   ---[ end trace bd187ee0267df5d9 ]---

To avoid this, set link->downstream in alloc_pcie_link_state(), so every
pcie_link_state structure has a valid link->downstream pointer.

[bhelgaas: changelog]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rajat Jain <rajatja@google.com>
CC: stable@vger.kernel.org
2017-03-07 14:23:30 -06:00
..
aer pci-v4.10-changes 2016-12-15 12:46:48 -08:00
aspm.c PCI/ASPM: Always set link->downstream to avoid NULL dereference on remove 2017-03-07 14:23:30 -06:00
Kconfig PCI/ASPM: Add support for L1 substates 2017-02-14 17:43:51 -06:00
Makefile PCI: Add Precision Time Measurement (PTM) support 2016-08-15 13:44:08 -05:00
pcie-dpc.c PCI/DPC: Wait for Root Port busy to clear 2017-02-10 14:36:14 -06:00
pme.c PCI/PME: Restore pcie_pme_driver.remove 2017-02-15 09:39:32 -06:00
portdrv_acpi.c Merge branches 'pci/dpc', 'pci/resource' and 'pci/thunderbolt' into next 2016-05-03 11:49:21 -05:00
portdrv_bus.c PCI: Fix whitespace, capitalization, and spelling errors 2013-11-14 11:28:18 -07:00
portdrv_core.c PCI/portdrv: Use pci_irq_alloc_vectors() 2017-02-10 16:06:12 -06:00
portdrv_pci.c PCI: Consolidate conditions to allow runtime PM on PCIe ports 2016-11-17 18:46:22 -06:00
portdrv.h Merge branches 'pci/dpc', 'pci/resource' and 'pci/thunderbolt' into next 2016-05-03 11:49:21 -05:00
ptm.c PCI: Add PTM clock granularity information 2016-08-25 08:32:34 -05:00