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Gao Xiang 33bf23c994 erofs: fix lz4 inplace decompression 
[ Upstream commit 3c12466b6b ]

Currently EROFS can map another compressed buffer for inplace
decompression, that was used to handle the cases that some pages of
compressed data are actually not in-place I/O.

However, like most simple LZ77 algorithms, LZ4 expects the compressed
data is arranged at the end of the decompressed buffer and it
explicitly uses memmove() to handle overlapping:
  __________________________________________________________
 |_ direction of decompression --> ____ |_ compressed data _|

Although EROFS arranges compressed data like this, it typically maps two
individual virtual buffers so the relative order is uncertain.
Previously, it was hardly observed since LZ4 only uses memmove() for
short overlapped literals and x86/arm64 memmove implementations seem to
completely cover it up and they don't have this issue.  Juhyung reported
that EROFS data corruption can be found on a new Intel x86 processor.
After some analysis, it seems that recent x86 processors with the new
FSRM feature expose this issue with "rep movsb".

Let's strictly use the decompressed buffer for lz4 inplace
decompression for now.  Later, as an useful improvement, we could try
to tie up these two buffers together in the correct order.

Reported-and-tested-by: Juhyung Park <qkrwngud825@gmail.com>
Closes: https://lore.kernel.org/r/CAD14+f2AVKf8Fa2OO1aAUdDNTDsVzzR6ctU_oJSmTyd6zSYR2Q@mail.gmail.com
Fixes: 0ffd71bcc3 ("staging: erofs: introduce LZ4 decompression inplace")
Fixes: 598162d050 ("erofs: support decompress big pcluster for lz4 backend")
Cc: stable <stable@vger.kernel.org> # 5.4+
Tested-by: Yifan Zhao <zhaoyifan@sjtu.edu.cn>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231206045534.3920847-1-hsiangkao@linux.alibaba.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-01-31 16:17:09 -08:00
arch LoongArch/smp: Call rcutree_report_cpu_starting() earlier 2024-01-31 16:17:03 -08:00
block block: Remove special-casing of compound pages 2024-01-25 15:27:52 -08:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: api - Disallow identical driver names 2024-01-31 16:16:58 -08:00
Documentation rename(): fix the locking of subdirectories 2024-01-31 16:17:02 -08:00
drivers drm/amdgpu/pm: Fix the power source flag error 2024-01-31 16:17:08 -08:00
fs erofs: fix lz4 inplace decompression 2024-01-31 16:17:09 -08:00
include btrfs: defrag: reject unknown flags of btrfs_ioctl_defrag_range_args 2024-01-31 16:17:07 -08:00
init rootfs: Fix support for rootfstype= when root= is given 2024-01-25 15:27:43 -08:00
io_uring io_uring/rw: ensure io->bytes_done is always initialized 2024-01-25 15:27:41 -08:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel rcu: Defer RCU kthreads wakeup when CPU is dying 2024-01-31 16:17:05 -08:00
lib kunit: debugfs: Fix unchecked dereference in debugfs_print_results() 2024-01-25 15:27:21 -08:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: page_alloc: unreserve highatomic page blocks before oom 2024-01-31 16:17:03 -08:00
net netfilter: nf_tables: reject QUEUE/DROP verdict parameters 2024-01-31 16:17:07 -08:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples fprobe: Pass entry_data to handlers 2023-10-25 12:03:12 +02:00
scripts scripts/get_abi: fix source path leak 2024-01-31 16:17:01 -08:00
security lsm: new security_file_ioctl_compat() hook 2024-01-31 16:17:00 -08:00
sound ASoC: mediatek: sof-common: Add NULL check for normal_link string 2024-01-25 15:27:48 -08:00
tools selftests: netdevsim: fix the udp_tunnel_nic test 2024-01-31 16:17:06 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +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 genirq/affinity: Move group_cpus_evenly() into lib/ 2024-01-10 17:10:33 +01:00
Makefile Linux 6.1.75 2024-01-25 15:27:52 -08:00
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.