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Linus Torvalds ac351de9dd BACKPORT: make 'user_access_begin()' do 'access_ok()' 
upstream commit 594cc251fd ("make 'user_access_begin()' do 'access_ok()'")

Originally, the rule used to be that you'd have to do access_ok()
separately, and then user_access_begin() before actually doing the
direct (optimized) user access.

But experience has shown that people then decide not to do access_ok()
at all, and instead rely on it being implied by other operations or
similar.  Which makes it very hard to verify that the access has
actually been range-checked.

If you use the unsafe direct user accesses, hardware features (either
SMAP - Supervisor Mode Access Protection - on x86, or PAN - Privileged
Access Never - on ARM) do force you to use user_access_begin().  But
nothing really forces the range check.

By putting the range check into user_access_begin(), we actually force
people to do the right thing (tm), and the range check vill be visible
near the actual accesses.  We have way too long a history of people
trying to avoid them.

Bug: 135368228
Change-Id: I4ca0e4566ea080fa148c5e768bb1a0b6f7201c01
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-12 11:28:03 +00:00
arch BACKPORT: make 'user_access_begin()' do 'access_ok()' 2019-09-12 11:28:03 +00:00
block This is the 4.19.69 stable release 2019-09-02 17:39:29 +02:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto This is the 4.19.61 stable release 2019-07-26 10:31:53 +02:00
Documentation This is the 4.19.69 stable release 2019-09-02 17:39:29 +02:00
drivers BACKPORT: make 'user_access_begin()' do 'access_ok()' 2019-09-12 11:28:03 +00:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs This is the 4.19.72 stable release 2019-09-10 10:48:21 +01:00
include BACKPORT: make 'user_access_begin()' do 'access_ok()' 2019-09-12 11:28:03 +00:00
init UPSTREAM: mm: init: report memory auto-initialization features at boot time 2019-08-30 11:58:40 +02:00
ipc This is the 4.19.65 stable release 2019-08-06 20:08:18 +02:00
kernel BACKPORT: make 'user_access_begin()' do 'access_ok()' 2019-09-12 11:28:03 +00:00
lib BACKPORT: make 'user_access_begin()' do 'access_ok()' 2019-09-12 11:28:03 +00:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm This is the 4.19.70 stable release 2019-09-06 12:08:42 +02:00
net This is the 4.19.72 stable release 2019-09-10 10:48:21 +01:00
samples samples, bpf: suppress compiler warning 2019-07-14 08:11:04 +02:00
scripts This is the 4.19.68 stable release 2019-08-25 14:19:34 +02:00
security UPSTREAM: mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options 2019-08-30 11:58:12 +02:00
sound Revert "ASoC: Fail card instantiation if DAI format setup fails" 2019-09-06 10:22:23 +02:00
tools This is the 4.19.72 stable release 2019-09-10 10:48:21 +01:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: arm/arm64: VGIC: Properly initialise private IRQ affinity 2019-09-10 10:33:53 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.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 updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
abi_gki_aarch64.xml ABI update for 4.19.72 2019-09-10 13:08:25 +01:00
build.config.gki.aarch64 Adding GKI Ramdisk to gki config 2019-08-14 18:17:18 +00:00
build.config.gki.x86_64 Adding GKI Ramdisk to gki config 2019-08-14 18:17:18 +00:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS platform/x86: Add Intel AtomISP2 dummy / power-management driver 2019-04-20 09:16:02 +02:00
Makefile This is the 4.19.72 stable release 2019-09-10 10:48:21 +01:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
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.