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Liam R. Howlett 9d5a3b4aee maple_tree: disable mas_wr_append() when other readers are possible 
[ Upstream commit cfeb6ae8bc ]

The current implementation of append may cause duplicate data and/or
incorrect ranges to be returned to a reader during an update.  Although
this has not been reported or seen, disable the append write operation
while the tree is in rcu mode out of an abundance of caution.

During the analysis of the mas_next_slot() the following was
artificially created by separating the writer and reader code:

Writer:                                 reader:
mas_wr_append
    set end pivot
    updates end metata
    Detects write to last slot
    last slot write is to start of slot
    store current contents in slot
    overwrite old end pivot
                                        mas_next_slot():
                                                read end metadata
                                                read old end pivot
                                                return with incorrect range
    store new value

Alternatively:

Writer:                                 reader:
mas_wr_append
    set end pivot
    updates end metata
    Detects write to last slot
    last lost write to end of slot
    store value
                                        mas_next_slot():
                                                read end metadata
                                                read old end pivot
                                                read new end pivot
                                                return with incorrect range
    set old end pivot

There may be other accesses that are not safe since we are now updating
both metadata and pointers, so disabling append if there could be rcu
readers is the safest action.

Link: https://lkml.kernel.org/r/20230819004356.1454718-2-Liam.Howlett@oracle.com
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-08-30 16:11:13 +02:00
arch x86/fpu: Set X86_FEATURE_OSXSAVE feature after enabling OSXSAVE in CR4 2023-08-30 16:11:09 +02:00
block blk-crypto: dynamically allocate fallback profile 2023-08-23 17:52:39 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: jitter - correct health test during initialization 2023-07-19 16:21:42 +02:00
Documentation x86/cpu: Rename srso_(.*)_alias to srso_alias_\1 2023-08-26 13:26:59 +02:00
drivers gpio: sim: pass the GPIO device's software node to irq domain 2023-08-30 16:11:13 +02:00
fs nfsd: use vfs setgid helper 2023-08-30 16:11:10 +02:00
include clk: Fix undefined reference to `clk_rate_exclusive_{get,put}' 2023-08-30 16:11:12 +02:00
init x86/mm: Initialize text poking earlier 2023-08-08 20:03:49 +02:00
io_uring io_uring/msg_ring: fix missing lock on overflow for IOPOLL 2023-08-30 16:11:05 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel cgroup/cpuset: Free DL BW in case can_attach() fails 2023-08-30 16:11:11 +02:00
lib maple_tree: disable mas_wr_append() when other readers are possible 2023-08-30 16:11:13 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm madvise:madvise_free_pte_range(): don't use mapcount() against large folio for sharing check 2023-08-30 16:11:11 +02:00
net can: raw: add missing refcount for memory leak fix 2023-08-30 16:11:11 +02:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples samples: ftrace: Save required argument registers in sample trampolines 2023-07-23 13:49:44 +02:00
scripts gcc-plugins: Reorganize gimple includes for GCC 13 2023-08-16 18:27:20 +02:00
security selinux: set next pointer before attaching to list 2023-08-30 16:11:07 +02:00
sound ASoC: amd: yc: Fix a non-functional mic on Lenovo 82SJ 2023-08-30 16:11:13 +02:00
tools selftests/net: mv bpf/nat6to4.c to net folder 2023-08-30 16:11:10 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-08-03 10:24:08 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS devlink: move code to a dedicated directory 2023-08-30 16:11:00 +02:00
Makefile Linux 6.1.49 2023-08-27 21:01:32 +02:00
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.