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Igor Mammedov 1900e193b5 PCI: acpiphp: Use pci_assign_unassigned_bridge_resources() only for non-root bus 
commit cc22522fd5 upstream.

40613da52b ("PCI: acpiphp: Reassign resources on bridge if necessary")
changed acpiphp hotplug to use pci_assign_unassigned_bridge_resources()
which depends on bridge being available, however enable_slot() can be
called without bridge associated:

  1. Legitimate case of hotplug on root bus (widely used in virt world)

  2. A (misbehaving) firmware, that sends ACPI Bus Check notifications to
     non existing root ports (Dell Inspiron 7352/0W6WV0), which end up at
     enable_slot(..., bridge = 0) where bus has no bridge assigned to it.
     acpihp doesn't know that it's a bridge, and bus specific 'PCI
     subsystem' can't augment ACPI context with bridge information since
     the PCI device to get this data from is/was not available.

Issue is easy to reproduce with QEMU's 'pc' machine, which supports PCI
hotplug on hostbridge slots. To reproduce, boot kernel at commit
40613da52b in VM started with following CLI (assuming guest root fs is
installed on sda1 partition):

  # qemu-system-x86_64 -M pc -m 1G -enable-kvm -cpu host \
        -monitor stdio -serial file:serial.log           \
        -kernel arch/x86/boot/bzImage                    \
        -append "root=/dev/sda1 console=ttyS0"           \
        guest_disk.img

Once guest OS is fully booted at qemu prompt:

  (qemu) device_add e1000

(check serial.log) it will cause NULL pointer dereference at:

  void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)
  {
    struct pci_bus *parent = bridge->subordinate;

  BUG: kernel NULL pointer dereference, address: 0000000000000018

   ? pci_assign_unassigned_bridge_resources+0x1f/0x260
   enable_slot+0x21f/0x3e0
   acpiphp_hotplug_notify+0x13d/0x260
   acpi_device_hotplug+0xbc/0x540
   acpi_hotplug_work_fn+0x15/0x20
   process_one_work+0x1f7/0x370
   worker_thread+0x45/0x3b0

The issue was discovered on Dell Inspiron 7352/0W6WV0 laptop with following
sequence:

  1. Suspend to RAM
  2. Wake up with the same backtrace being observed:
  3. 2nd suspend to RAM attempt makes laptop freeze

Fix it by using __pci_bus_assign_resources() instead of
pci_assign_unassigned_bridge_resources() as we used to do, but only in case
when bus doesn't have a bridge associated (to cover for the case of ACPI
event on hostbridge or non existing root port).

That lets us keep hotplug on root bus working like it used to and at the
same time keeps resource reassignment usable on root ports (and other 1st
level bridges) that was fixed by 40613da52b.

Fixes: 40613da52b ("PCI: acpiphp: Reassign resources on bridge if necessary")
Link: https://lore.kernel.org/r/20230726123518.2361181-2-imammedo@redhat.com
Reported-by: Woody Suwalski <terraluna977@gmail.com>
Tested-by: Woody Suwalski <terraluna977@gmail.com>
Tested-by: Michal Koutný <mkoutny@suse.com>
Link: https://lore.kernel.org/r/11fc981c-af49-ce64-6b43-3e282728bd1a@gmail.com
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2023-08-30 16:11:09 +02:00
arch riscv: Fix build errors using binutils2.37 toolchains 2023-08-30 16:11:08 +02:00
block blk-crypto: dynamically allocate fallback profile 2023-08-23 17:52:39 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: jitter - correct health test during initialization 2023-07-19 16:21:42 +02:00
Documentation x86/cpu: Rename srso_(.*)_alias to srso_alias_\1 2023-08-26 13:26:59 +02:00
drivers PCI: acpiphp: Use pci_assign_unassigned_bridge_resources() only for non-root bus 2023-08-30 16:11:09 +02:00
fs nfsd: Fix race to FREE_STATEID and cl_revoked 2023-08-30 16:11:07 +02:00
include mm/gup: handle cont-PTE hugetlb pages correctly in gup_must_unshare() via GUP-fast 2023-08-30 16:11:06 +02:00
init x86/mm: Initialize text poking earlier 2023-08-08 20:03:49 +02:00
io_uring io_uring/msg_ring: fix missing lock on overflow for IOPOLL 2023-08-30 16:11:05 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel tracing: Fix memleak due to race between current_tracer and trace 2023-08-30 16:11:00 +02:00
lib radix tree: remove unused variable 2023-08-30 16:11:08 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: memory-failure: fix unexpected return value in soft_offline_page() 2023-08-30 16:11:06 +02:00
net batman-adv: Hold rtnl lock during MTU update via netlink 2023-08-30 16:11:08 +02:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples samples: ftrace: Save required argument registers in sample trampolines 2023-07-23 13:49:44 +02:00
scripts gcc-plugins: Reorganize gimple includes for GCC 13 2023-08-16 18:27:20 +02:00
security selinux: set next pointer before attaching to list 2023-08-30 16:11:07 +02:00
sound ALSA: ymfpci: Fix the missing snd_card_free() call at probe error 2023-08-30 16:11:06 +02:00
tools selftests: bonding: do not set port down before adding to bond 2023-08-30 16:11:02 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-08-03 10:24:08 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS devlink: move code to a dedicated directory 2023-08-30 16:11:00 +02:00
Makefile Linux 6.1.49 2023-08-27 21:01:32 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.