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Kees Cook 22ec1a2aea /dev/mem: Add bounce buffer for copy-out
As done for /proc/kcore in

  commit df04abfd18 ("fs/proc/kcore.c: Add bounce buffer for ktext data")

this adds a bounce buffer when reading memory via /dev/mem. This
is needed to allow kernel text memory to be read out when built with
CONFIG_HARDENED_USERCOPY (which refuses to read out kernel text) and
without CONFIG_STRICT_DEVMEM (which would have refused to read any RAM
contents at all).

Since this build configuration isn't common (most systems with
CONFIG_HARDENED_USERCOPY also have CONFIG_STRICT_DEVMEM), this also tries
to inform Kconfig about the recommended settings.

This patch is modified from Brad Spengler/PaX Team's changes to /dev/mem
code in the last public patch of grsecurity/PaX based on my understanding
of the code. Changes or omissions from the original code are mine and
don't reflect the original grsecurity/PaX code.

Reported-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Fixes: f5509cc18d ("mm: Hardened usercopy")
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-18 15:59:17 +01:00
Documentation Merge 4.15-rc3 into char-misc-next 2017-12-11 08:47:41 +01:00
arch ARM: SoC fixes for 4.15-rc 2017-12-10 08:26:59 -08:00
block Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-12-01 08:05:45 -05:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto X.509: fix comparisons of ->pkey_algo 2017-12-08 15:13:29 +00:00
drivers /dev/mem: Add bounce buffer for copy-out 2017-12-18 15:59:17 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs hpfs: don't bother with the i_version counter or f_version 2017-12-10 12:58:18 -08:00
include Merge 4.15-rc3 into char-misc-next 2017-12-11 08:47:41 +01:00
init EXPERT Kconfig menu: fix broken EXPERT menu 2017-11-17 16:10:05 -08:00
ipc Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
kernel futex: futex_wake_op, fix sign_extend32 sign bits 2017-12-10 12:50:57 -08:00
lib Keyrings fixes 2017-12-09 14:39:48 +11:00
mm kmemcheck: rip it out for real 2017-12-08 13:40:17 -08:00
net tcp: evaluate packet losses upon RTT change 2017-12-08 14:14:11 -05:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2017-12-03 13:08:30 -05:00
scripts A handful of documentation fixes. The most significant of these addresses 2017-12-04 13:55:28 -08:00
security /dev/mem: Add bounce buffer for copy-out 2017-12-18 15:59:17 +01:00
sound sound fixes for 4.15-rc3 2017-12-06 10:49:14 -08:00
tools Merge 4.15-rc3 into char-misc-next 2017-12-11 08:47:41 +01:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: x86: fix APIC page invalidation 2017-12-06 16:10:34 +01:00
.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 misc updates for v4.15 2017-11-17 17:51:33 -08:00
.mailmap Add Jason Gunthorpe as co-maintainer of the RDMA stack 2017-11-17 09:36:18 -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 Merge 4.15-rc3 into char-misc-next 2017-12-11 08:47:41 +01:00
Makefile Linux 4.15-rc3 2017-12-10 17:56:26 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README

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.