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Daniel Thompson 281d356a03 lockdown: also lock down previous kgdb use
commit eadb2f47a3 upstream.

KGDB and KDB allow read and write access to kernel memory, and thus
should be restricted during lockdown.  An attacker with access to a
serial port (for example, via a hypervisor console, which some cloud
vendors provide over the network) could trigger the debugger so it is
important that the debugger respect the lockdown mode when/if it is
triggered.

Fix this by integrating lockdown into kdb's existing permissions
mechanism.  Unfortunately kgdb does not have any permissions mechanism
(although it certainly could be added later) so, for now, kgdb is simply
and brutally disabled by immediately exiting the gdb stub without taking
any action.

For lockdowns established early in the boot (e.g. the normal case) then
this should be fine but on systems where kgdb has set breakpoints before
the lockdown is enacted than "bad things" will happen.

CVE: CVE-2022-21499
Co-developed-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-25 09:59:10 +02:00
Documentation dt-bindings: pci: apple,pcie: Drop max-link-speed from example 2022-05-12 12:32:38 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch ARM: 9197/1: spectre-bhb: fix loop8 sequence for Thumb2 2022-05-25 09:59:10 +02:00
block block/mq-deadline: Set the fifo_time member also if inserting at head 2022-05-25 09:59:06 +02:00
certs certs: Fix build error when CONFIG_MODULE_SIG_KEY is empty 2022-01-23 00:08:44 +09:00
crypto crypto: xts - Add softdep on ecb 2022-04-08 13:58:36 +02:00
drivers net/mlx5: Drain fw_reset when removing device 2022-05-25 09:59:10 +02:00
fs nilfs2: fix lockdep warnings during disk space reclamation 2022-05-25 09:59:02 +02:00
include lockdown: also lock down previous kgdb use 2022-05-25 09:59:10 +02:00
init init/main.c: return 1 from handled __setup() functions 2022-04-13 19:27:23 +02:00
ipc ipc/sem: do not sleep with a spin lock held 2022-02-04 09:25:05 -08:00
kernel lockdown: also lock down previous kgdb use 2022-05-25 09:59:10 +02:00
lib dim: initialize all struct fields 2022-05-18 10:28:14 +02:00
mm mm/kfence: reset PG_slab and memcg_data before freeing __kfence_pool 2022-05-18 10:28:23 +02:00
net net: af_key: add check for pfkey_broadcast in function pfkey_process 2022-05-25 09:59:10 +02:00
samples samples/bpf, xdpsock: Fix race when running for fix duration of time 2022-04-08 13:58:18 +02:00
scripts kconfig: add fflush() before ferror() check 2022-05-25 09:58:59 +02:00
security lockdown: also lock down previous kgdb use 2022-05-25 09:59:10 +02:00
sound ALSA: hda - fix unused Realtek function when PM is not enabled 2022-05-25 09:59:05 +02:00
tools tools/virtio: compile with -pthread 2022-05-25 09:59:00 +02:00
usr kbuild: remove include/linux/cyclades.h from header file check 2022-01-27 08:51:08 +01:00
virt KVM: Free new dirty bitmap if creating a new memslot fails 2022-05-25 09:59:03 +02:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap MAINTAINERS: Update Jisheng's email address 2022-03-08 17:30:32 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS net: dsa: realtek-smi: move to subdirectory 2022-04-08 13:58:12 +02:00
Makefile Linux 5.17.9 2022-05-18 10:28:23 +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.