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Peter Zijlstra b31bac0619 x86/iopl: Fake iopl(3) CLI/STI usage
commit b968e84b509da593c50dc3db679e1d33de701f78 upstream.

Since commit c8137ace56 ("x86/iopl: Restrict iopl() permission
scope") it's possible to emulate iopl(3) using ioperm(), except for
the CLI/STI usage.

Userspace CLI/STI usage is very dubious (read broken), since any
exception taken during that window can lead to rescheduling anyway (or
worse). The IOPL(2) manpage even states that usage of CLI/STI is highly
discouraged and might even crash the system.

Of course, that won't stop people and HP has the dubious honour of
being the first vendor to be found using this in their hp-health
package.

In order to enable this 'software' to still 'work', have the #GP treat
the CLI/STI instructions as NOPs when iopl(3). Warn the user that
their program is doing dubious things.

Fixes: a24ca99768 ("x86/iopl: Remove legacy IOPL option")
Reported-by: Ondrej Zary <linux@zary.sk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org # v5.5+
Link: https://lkml.kernel.org/r/20210918090641.GD5106@worktop.programming.kicks-ass.net
Signed-off-by: Ondrej Zary <linux@zary.sk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-21 13:46:36 +01:00
arch x86/iopl: Fake iopl(3) CLI/STI usage 2021-11-21 13:46:36 +01:00
block block: remove inaccurate requeue check 2021-11-18 14:03:58 +01:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:50:29 +02:00
crypto crypto: pcrypt - Delay write to padata->info 2021-11-18 14:04:12 +01:00
Documentation fscrypt: allow 256-bit master keys with AES-256-XTS 2021-11-18 14:03:54 +01:00
drivers net: stmmac: dwmac-rk: fix unbalanced pm_runtime_enable warnings 2021-11-21 13:46:36 +01:00
fs f2fs: should use GFP_NOFS for directory inodes 2021-11-18 14:04:29 +01:00
include block: Add a helper to validate the block size 2021-11-21 13:46:35 +01:00
init bootconfig: init: Fix memblock leak in xbc_make_cmdline() 2021-11-21 13:46:35 +01:00
ipc ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry 2021-05-26 12:06:54 +02:00
kernel posix-cpu-timers: Clear task::posix_cputimers_work in copy_process() 2021-11-18 14:04:29 +01:00
lib lib/xz: Validate the value before assigning it to an enum variable 2021-11-18 14:03:58 +01:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm, oom: do not trigger out_of_memory from the #PF 2021-11-18 14:04:30 +01:00
net SUNRPC: Partial revert of commit 6f9f17287e 2021-11-18 14:04:32 +01:00
samples samples/kretprobes: Fix return value if register_kretprobe() failed 2021-11-18 14:04:11 +01:00
scripts leaking_addresses: Always print a trailing newline 2021-11-18 14:03:57 +01:00
security fortify: Explicitly disable Clang support 2021-11-21 13:46:35 +01:00
sound ASoC: cs42l42: Correct configuring of switch inversion from ts-inv 2021-11-18 14:04:21 +01:00
tools selftests/bpf: Fix also no-alu32 strobemeta selftest 2021-11-18 14:04:32 +01:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: do not shrink halt_poll_ns below grow_start 2021-10-09 14:40:58 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +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 f2fs: move ioctl interface definitions to separated file 2021-05-19 10:13:00 +02:00
Makefile Linux 5.10.80 2021-11-18 14:04:33 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.