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Masami Hiramatsu 74c515e049 kprobes: Set unoptimized flag after unoptimizing code 
commit f66c0447cc upstream.

Set the unoptimized flag after confirming the code is completely
unoptimized. Without this fix, when a kprobe hits the intermediate
modified instruction (the first byte is replaced by an INT3, but
later bytes can still be a jump address operand) while unoptimizing,
it can return to the middle byte of the modified code, which causes
an invalid instruction exception in the kernel.

Usually, this is a rare case, but if we put a probe on the function
call while text patching, it always causes a kernel panic as below:

 # echo p text_poke+5 > kprobe_events
 # echo 1 > events/kprobes/enable
 # echo 0 > events/kprobes/enable

invalid opcode: 0000 [#1] PREEMPT SMP PTI
 RIP: 0010:text_poke+0x9/0x50
 Call Trace:
  arch_unoptimize_kprobe+0x22/0x28
  arch_unoptimize_kprobes+0x39/0x87
  kprobe_optimizer+0x6e/0x290
  process_one_work+0x2a0/0x610
  worker_thread+0x28/0x3d0
  ? process_one_work+0x610/0x610
  kthread+0x10d/0x130
  ? kthread_park+0x80/0x80
  ret_from_fork+0x3a/0x50

text_poke() is used for patching the code in optprobes.

This can happen even if we blacklist text_poke() and other functions,
because there is a small time window during which we show the intermediate
code to other CPUs.

 [ mingo: Edited the changelog. ]

Tested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Fixes: 6274de4984 ("kprobes: Support delayed unoptimizing")
Link: https://lkml.kernel.org/r/157483422375.25881.13508326028469515760.stgit@devnote2
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2020-03-05 16:43:49 +01:00
Documentation kbuild: remove header compile test 2020-03-05 16:43:47 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch KVM: SVM: Override default MMIO mask if memory encryption is enabled 2020-03-05 16:43:48 +01:00
block block, bfq: do not plug I/O for bfq_queues with no proc refs 2020-02-24 08:36:31 +01:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto crypto: rename sm3-256 to sm3 in hash_algo_name 2020-02-28 17:22:26 +01:00
drivers drivers: net: xgene: Fix the order of the arguments of 'alloc_etherdev_mqs()' 2020-03-05 16:43:49 +01:00
fs f2fs: fix to add swap extent correctly 2020-03-05 16:43:48 +01:00
include kbuild: remove header compile test 2020-03-05 16:43:47 +01:00
init kbuild: remove header compile test 2020-03-05 16:43:47 +01:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-28 17:22:20 +01:00
kernel kprobes: Set unoptimized flag after unoptimizing code 2020-03-05 16:43:49 +01:00
lib kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
mm mm: Avoid creating virtual address aliases in brk()/mmap()/mremap() 2020-02-28 17:22:21 +01:00
net net/smc: no peer ID in CLC decline for SMCD 2020-03-05 16:43:47 +01:00
samples samples/bpf: Set -fno-stack-protector when building BPF programs 2020-02-24 08:36:36 +01:00
scripts kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
security ima: ima/lsm policy rule loading logic bug fixes 2020-03-05 16:43:49 +01:00
sound ASoC: SOF: Intel: hda: Add iDisp4 DAI 2020-02-28 17:22:29 +01:00
tools selftests: Install settings files to fix TIMEOUT failures 2020-03-05 16:43:47 +01:00
usr kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
virt KVM: Check for a bad hva before dropping into the ghc slow path 2020-03-05 16:43:48 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
…
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 17:22:19 +01:00
Makefile kbuild: make single target builds even faster 2020-03-05 16:43:48 +01:00
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.