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Nicholas Piggin e7bde88cdb powerpc/powernv: IMC fix out of bounds memory access at shutdown
The OPAL IMC driver's shutdown handler disables nest PMU counters by
walking nodes and taking the first CPU out of their cpumask, which is
used to index into the paca (get_hard_smp_processor_id()). This does
not always do the right thing, and in particular for CPU-less nodes it
returns NR_CPUS and that overruns the paca and dereferences random
memory.

Fix it by being more careful about checking returned CPU, and only
using online CPUs. It's not clear this shutdown code makes sense after
commit 885dcd709b ("powerpc/perf: Add nest IMC PMU support"), but this
should not make things worse

Currently the bug causes us to call OPAL with a junk CPU number. A
separate patch in development to change the way pacas are allocated
escalates this bug into a crash:

  Unable to handle kernel paging request for data at address 0x2a21af1eeb000076
  Faulting instruction address: 0xc0000000000a5468
  Oops: Kernel access of bad area, sig: 11 [#1]
  ...
  NIP opal_imc_counters_shutdown+0x148/0x1d0
  LR  opal_imc_counters_shutdown+0x134/0x1d0
  Call Trace:
   opal_imc_counters_shutdown+0x134/0x1d0 (unreliable)
   platform_drv_shutdown+0x44/0x60
   device_shutdown+0x1f8/0x350
   kernel_restart_prepare+0x54/0x70
   kernel_restart+0x28/0xc0
   SyS_reboot+0x1d0/0x2c0
   system_call+0x58/0x6c

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2018-02-15 09:54:45 +11:00
arch powerpc/powernv: IMC fix out of bounds memory access at shutdown 2018-02-15 09:54:45 +11:00
block vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-02-12 08:57:21 -08:00
Documentation MIPS changes for 4.16-rc2 2018-02-13 09:35:17 -08:00
drivers powerpc fixes for 4.16 #2 2018-02-14 10:06:41 -08:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
include Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-02-12 08:57:21 -08:00
init membarrier: Provide core serializing command, *_SYNC_CORE 2018-02-05 21:35:03 +01:00
ipc vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
kernel vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
lib Kbuild updates for v4.16 (2nd) 2018-02-09 19:32:41 -08:00
LICENSES LICENSES: Add MPL-1.1 license 2018-01-06 10:59:44 -07:00
mm vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
net vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
samples sample/bpf: fix erspan metadata 2018-02-06 11:32:49 -05:00
scripts Kbuild updates for v4.16 (2nd) 2018-02-09 19:32:41 -08:00
security vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
sound vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
tools powerpc fixes for 4.16 #2 2018-02-14 10:06:41 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
.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 scripts/package: snap-pkg target 2017-12-13 00:00:18 +09:00
.mailmap mailmap: update Mark Yao's email address 2018-01-04 16:45:09 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS MIPS changes for 4.16-rc2 2018-02-13 09:35:17 -08:00
Makefile Linux 4.16-rc1 2018-02-11 15:04:29 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.