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Qian Cai cda099b37d fork: Annotate a data race in vm_area_dup()
struct vm_area_struct could be accessed concurrently as noticed by
KCSAN,

 write to 0xffff9cf8bba08ad8 of 8 bytes by task 14263 on cpu 35:
  vma_interval_tree_insert+0x101/0x150:
  rb_insert_augmented_cached at include/linux/rbtree_augmented.h:58
  (inlined by) vma_interval_tree_insert at mm/interval_tree.c:23
  __vma_link_file+0x6e/0xe0
  __vma_link_file at mm/mmap.c:629
  vma_link+0xa2/0x120
  mmap_region+0x753/0xb90
  do_mmap+0x45c/0x710
  vm_mmap_pgoff+0xc0/0x130
  ksys_mmap_pgoff+0x1d1/0x300
  __x64_sys_mmap+0x33/0x40
  do_syscall_64+0x91/0xc44
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

 read to 0xffff9cf8bba08a80 of 200 bytes by task 14262 on cpu 122:
  vm_area_dup+0x6a/0xe0
  vm_area_dup at kernel/fork.c:362
  __split_vma+0x72/0x2a0
  __split_vma at mm/mmap.c:2661
  split_vma+0x5a/0x80
  mprotect_fixup+0x368/0x3f0
  do_mprotect_pkey+0x263/0x420
  __x64_sys_mprotect+0x51/0x70
  do_syscall_64+0x91/0xc44
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

vm_area_dup() blindly copies all fields of original VMA to the new one.
This includes coping vm_area_struct::shared.rb which is normally
protected by i_mmap_lock. But this is fine because the read value will
be overwritten on the following __vma_link_file() under proper
protection. Thus, mark it as an intentional data race and insert a few
assertions for the fields that should not be modified concurrently.

Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
History 2020-06-29 12:04:47 -07:00
arch ARM: OMAP fixes for v5.8 2020-06-28 14:57:14 -07:00
block block-5.8-2020-06-26 2020-06-27 08:59:32 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto crypto: drbg - always try to free Jitter RNG instance 2020-06-15 17:38:54 +10:00
Documentation Peter Zijlstra says: 2020-06-28 09:42:47 -07:00
drivers ARM: OMAP fixes for v5.8 2020-06-28 14:57:14 -07:00
fs - Fix build regression on v4.8 and older 2020-06-28 11:42:16 -07:00
include A single DocBook fix. 2020-06-28 11:59:08 -07:00
init Kbuild updates for v5.8 (2nd) 2020-06-13 13:29:16 -07:00
ipc mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
kernel fork: Annotate a data race in vm_area_dup() 2020-06-29 12:04:47 -07:00
lib Peter Zijlstra says: 2020-06-28 09:42:47 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/memory_hotplug.c: fix false softlockup during pfn range removal 2020-06-26 00:27:38 -07:00
net NFS Client Bugfixes for Linux 5.8-rc 2020-06-27 09:35:47 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-06-25 18:27:40 -07:00
scripts Paul E. McKenney says: 2020-06-28 10:29:38 -07:00
security selinux/stable-5.8 PR 20200621 2020-06-21 15:41:24 -07:00
sound sound fixes for 5.8-rc3 2020-06-25 09:15:24 -07:00
tools Peter Zijlstra says: 2020-06-28 10:16:15 -07:00
usr bpfilter: match bit size of bpfilter_umh to that of the kernel 2020-05-17 18:52:01 +09:00
virt MIPS: 2020-06-12 11:05:52 -07:00
.clang-format block: add bio_for_each_bvec_all() 2020-05-25 11:25:24 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 modpost: generate vmlinux.symvers and reuse it for the second modpost 2020-06-06 23:38:12 +09:00
.mailmap A fair amount of stuff this time around, dominated by yet another massive 2020-06-01 15:45:27 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS mailmap: change email for Ricardo Ribalda 2020-05-25 18:59:59 -06:00
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 ARM: SoC fixes for v5.8 2020-06-28 14:55:18 -07:00
Makefile Linux 5.8-rc3 2020-06-28 15:00:24 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.