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Logan Gunthorpe d2fd6e8191 PCI: Fix __initdata issue with "pci=disable_acs_redir" parameter
The disable_acs_redir parameter stores a pointer to the string passed to
pci_setup().  However, the string passed to PCI setup is actually a
temporary copy allocated in static __initdata memory.  After init, once the
memory is freed, it is no longer valid to reference this pointer.

This bug was noticed in v5.0-rc1 after a change in commit c5eb119007
("PCI / PM: Allow runtime PM without callback functions") caused
pci_disable_acs_redir() to be called during shutdown which manifested
as an unable to handle kernel paging request at:

  RIP: 0010:pci_enable_acs+0x3f/0x1e0
  Call Trace:
     pci_restore_state.part.44+0x159/0x3c0
     pci_restore_standard_config+0x33/0x40
     pci_pm_runtime_resume+0x2b/0xd0
     ? pci_restore_standard_config+0x40/0x40
     __rpm_callback+0xbc/0x1b0
     rpm_callback+0x1f/0x70
     ? pci_restore_standard_config+0x40/0x40
      rpm_resume+0x4f9/0x710
     ? pci_conf1_read+0xb6/0xf0
     ? pci_conf1_write+0xb2/0xe0
     __pm_runtime_resume+0x47/0x70
     pci_device_shutdown+0x1e/0x60
     device_shutdown+0x14a/0x1f0
     kernel_restart+0xe/0x50
     __do_sys_reboot+0x1ee/0x210
     ? __fput+0x144/0x1d0
     do_writev+0x5e/0xf0
     ? do_writev+0x5e/0xf0
     do_syscall_64+0x48/0xf0
     entry_SYSCALL_64_after_hwframe+0x44/0xa9

It was also likely possible to trigger this bug when hotplugging PCI
devices.

To fix this, instead of storing a pointer, we use kstrdup() to copy the
disable_acs_redir_param to its own buffer which will never be freed.

Fixes: aaca43fda7 ("PCI: Add "pci=disable_acs_redir=" parameter for peer-to-peer support")
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
2019-01-17 08:46:34 -06:00
Documentation Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
arch Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
block for-4.21/block-20190102 2019-01-02 18:49:58 -08:00
certs kbuild: remove redundant target cleaning on failure 2019-01-06 09:46:51 +09:00
crypto Kconfig updates for v4.21 2018-12-29 13:03:29 -08:00
drivers PCI: Fix __initdata issue with "pci=disable_acs_redir" parameter 2019-01-17 08:46:34 -06:00
firmware kbuild: change filechk to surround the given command with { } 2019-01-06 09:46:51 +09:00
fs Add Adiantum support for fscrypt 2019-01-06 12:21:11 -08:00
include Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
init jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
lib Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
mm Change mincore() to count "mapped" pages rather than "cached" pages 2019-01-06 13:43:02 -08:00
net jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00
samples Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid 2019-01-05 17:53:40 -08:00
scripts kconfig: rename generated .*conf-cfg to *conf-cfg 2019-01-06 10:47:09 +09:00
security Merge branch 'mount.part1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-01-05 13:25:58 -08:00
sound Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
tools Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt Merge branch 'akpm' (patches from Andrew) 2019-01-05 09:16:18 -08:00
.clang-format page cache: Convert find_get_pages_contig to XArray 2018-10-21 10:46:34 -04:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support for DT binding schema checks 2018-12-13 09:41:32 -06:00
.mailmap A few early MIPS fixes for 4.21: 2019-01-05 12:48:25 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Add CREDITS entry for Shaohua Li 2019-01-04 14:27:09 -07:00
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS chrome platform changes for v4.21 2019-01-06 11:40:06 -08:00
Makefile Linux 5.0-rc1 2019-01-06 17:08:20 -08:00
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.