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Rasmus Villemoes 03f6cbbde2 include/linux/bitops.h: sanitize rotate primitives 
commit ef4d6f6b27 upstream.

The ror32 implementation (word >> shift) | (word << (32 - shift) has
undefined behaviour if shift is outside the [1, 31] range.  Similarly
for the 64 bit variants.  Most callers pass a compile-time constant
(naturally in that range), but there's an UBSAN report that these may
actually be called with a shift count of 0.

Instead of special-casing that, we can make them DTRT for all values of
shift while also avoiding UB.  For some reason, this was already partly
done for rol32 (which was well-defined for [0, 31]).  gcc 8 recognizes
these patterns as rotates, so for example

  __u32 rol32(__u32 word, unsigned int shift)
  {
	return (word << (shift & 31)) | (word >> ((-shift) & 31));
  }

compiles to

0000000000000020 <rol32>:
  20:   89 f8                   mov    %edi,%eax
  22:   89 f1                   mov    %esi,%ecx
  24:   d3 c0                   rol    %cl,%eax
  26:   c3                      retq

Older compilers unfortunately do not do as well, but this only affects
the small minority of users that don't pass constants.

Due to integer promotions, ro[lr]8 were already well-defined for shifts
in [0, 8], and ro[lr]16 were mostly well-defined for shifts in [0, 16]
(only mostly - u16 gets promoted to _signed_ int, so if bit 15 is set,
word << 16 is undefined).  For consistency, update those as well.

Link: http://lkml.kernel.org/r/20190410211906.2190-1-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reported-by: Ido Schimmel <idosch@mellanox.com>
Tested-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Cc: Vadim Pasternak <vadimp@mellanox.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-09 09:18:13 +02:00
arch sparc64: Fix regression in non-hypervisor TLB flush xcall 2019-06-09 09:18:13 +02:00
block block: sed-opal: fix IOC_OPAL_ENABLE_DISABLE_MBR 2019-05-31 06:47:29 -07:00
certs Replace magic for trusting the secondary keyring with #define 2018-09-09 19:55:54 +02:00
crypto crypto: ccm - fix incompatibility between "ccm" and "ccm_base" 2019-05-21 18:50:20 +02:00
Documentation x86/speculation/mds: Improve CPU buffer clear documentation 2019-05-21 18:50:13 +02:00
drivers xen/pciback: Don't disable PCI_COMMAND on PCI device reset. 2019-06-09 09:18:12 +02:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs NFS: Fix a double unlock from nfs_match,get_client 2019-05-31 06:47:35 -07:00
include include/linux/bitops.h: sanitize rotate primitives 2019-06-09 09:18:13 +02:00
init init: initialize jump labels before command line option parsing 2019-05-16 19:42:23 +02:00
ipc ipc/sem.c: prevent queue.status tearing in semop 2018-09-05 09:26:30 +02:00
kernel rcuperf: Fix cleanup path for invalid perf_type strings 2019-05-31 06:47:33 -07:00
lib kobject: Don't trigger kobject_uevent(KOBJ_REMOVE) twice. 2019-05-31 06:47:32 -07:00
mm hugetlb: use same fault hash key for shared and private mappings 2019-05-31 06:47:12 -07:00
net tipc: fix modprobe tipc failed after switch order of device registration 2019-06-09 09:18:12 +02:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-02-15 08:09:12 +01:00
scripts kconfig/[mn]conf: handle backspace (^H) key 2019-05-04 09:15:22 +02:00
security apparmorfs: fix use-after-free on symlink traversal 2019-05-25 18:25:35 +02:00
sound ASoC: davinci-mcasp: Fix clang warning without CONFIG_PM 2019-05-31 06:47:35 -07:00
tools libbpf: fix samples/bpf build failure due to undefined UINT32_MAX 2019-05-31 06:47:22 -07:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: arm/arm64: Ensure vcpu target is unset on reset failure 2019-05-25 18:25:35 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS MAINTAINERS: Add Sasha as a stable branch maintainer 2018-12-01 09:42:50 +01:00
Makefile Linux 4.14.123 2019-05-31 06:47:36 -07:00
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.