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Manfred Spraul 17d056e0bd ipc/sem.c: use READ_ONCE()/WRITE_ONCE() for use_global_lock 
The patch solves three weaknesses in ipc/sem.c:

1) The initial read of use_global_lock in sem_lock() is an intentional
   race.  KCSAN detects these accesses and prints a warning.

2) The code assumes that plain C read/writes are not mangled by the CPU
   or the compiler.

3) The comment it sysvipc_sem_proc_show() was hard to understand: The
   rest of the comments in ipc/sem.c speaks about sem_perm.lock, and
   suddenly this function speaks about ipc_lock_object().

To solve 1) and 2), use READ_ONCE()/WRITE_ONCE().  Plain C reads are used
in code that owns sma->sem_perm.lock.

The comment is updated to solve 3)

[manfred@colorfullife.com: use READ_ONCE()/WRITE_ONCE() for use_global_lock]
  Link: https://lkml.kernel.org/r/20210627161919.3196-3-manfred@colorfullife.com

Link: https://lkml.kernel.org/r/20210514175319.12195-1-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: <1vier1@web.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-01 11:06:07 -07:00
arch kprobes: remove duplicated strong free_insn_page in x86 and s390 2021-07-01 11:06:06 -07:00
block block-5.13-2021-05-22 2021-05-22 07:40:34 -10:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
crypto async_xor: check src_offs is not NULL before updating it 2021-06-10 19:40:14 -07:00
Documentation kernel.h: split out kstrtox() and simple_strtox() to a separate header 2021-07-01 11:06:05 -07:00
drivers kernel.h: split out panic and oops helpers 2021-07-01 11:06:04 -07:00
fs exec: remove checks in __register_bimfmt() 2021-07-01 11:06:06 -07:00
include kcov: add __no_sanitize_coverage to fix noinstr for all architectures 2021-07-01 11:06:06 -07:00
init init: print out unknown kernel parameters 2021-07-01 11:06:06 -07:00
ipc ipc/sem.c: use READ_ONCE()/WRITE_ONCE() for use_global_lock 2021-07-01 11:06:07 -07:00
kernel x86: signal: don't do sas_ss_reset() until we are certain that sigframe won't be abandoned 2021-07-01 11:06:06 -07:00
lib lib/decompressors: remove set but not used variabled 'level' 2021-07-01 11:06:06 -07:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm mm: device exclusive memory access 2021-07-01 11:06:03 -07:00
net net/ipv5/tcp: use vma_lookup() in tcp_zerocopy_receive() 2021-06-29 10:53:51 -07:00
samples VFIO fixes for v5.13-rc5 2021-06-03 11:52:24 -07:00
scripts checkpatch: do not complain about positive return values starting with EPOLL 2021-07-01 11:06:06 -07:00
security trusted-keys: match tpm_get_ops on all return paths 2021-05-12 22:36:37 +03:00
sound ASoC: rt5645: Avoid upgrading static warnings to errors 2021-06-24 12:22:27 +02:00
tools selftests/vm/pkeys: exercise x86 XSAVE init state 2021-07-01 11:06:06 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt virt/kvm: use vma_lookup() instead of find_vma_intersection() 2021-06-29 10:53:51 -07:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Marek's other e-mail address and identity without diacritics 2021-06-24 19:40:54 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add myself as designated reviewer for generic string library 2021-07-01 11:06:05 -07:00
Makefile Linux 5.13 2021-06-27 15:21:11 -07:00
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.