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Dave Rodgman b5265c813c lib/lzo: fix ambiguous encoding bug in lzo-rle
In some rare cases, for input data over 32 KB, lzo-rle could encode two
different inputs to the same compressed representation, so that
decompression is then ambiguous (i.e.  data may be corrupted - although
zram is not affected because it operates over 4 KB pages).

This modifies the compressor without changing the decompressor or the
bitstream format, such that:

 - there is no change to how data produced by the old compressor is
   decompressed

 - an old decompressor will correctly decode data from the updated
   compressor

 - performance and compression ratio are not affected

 - we avoid introducing a new bitstream format

In testing over 12.8M real-world files totalling 903 GB, three files
were affected by this bug.  I also constructed 37M semi-random 64 KB
files totalling 2.27 TB, and saw no affected files.  Finally I tested
over files constructed to contain each of the ~1024 possible bad input
sequences; for all of these cases, updated lzo-rle worked correctly.

There is no significant impact to performance or compression ratio.

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Dave Rodgman <dave.rodgman@arm.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Markus F.X.J. Oberhumer <markus@oberhumer.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200507100203.29785-1-dave.rodgman@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-11 18:17:47 -07:00
arch Merge branch 'akpm' (patches from Andrew) 2020-06-11 13:25:53 -07:00
block for-5.8/drivers-2020-06-01 2020-06-02 15:37:03 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto Merge branch 'rwonce/rework' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux 2020-06-10 14:46:54 -07:00
Documentation lib/lzo: fix ambiguous encoding bug in lzo-rle 2020-06-11 18:17:47 -07:00
drivers Merge branch 'akpm' (patches from Andrew) 2020-06-11 13:25:53 -07:00
fs ocfs2: fix build failure when TCP/IP is disabled 2020-06-11 18:17:47 -07:00
include Merge branch 'akpm' (patches from Andrew) 2020-06-11 13:25:53 -07:00
init Merge branch 'rwonce/rework' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux 2020-06-10 14:46:54 -07:00
ipc mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
kernel Merge branch 'akpm' (patches from Andrew) 2020-06-11 13:25:53 -07:00
lib lib/lzo: fix ambiguous encoding bug in lzo-rle 2020-06-11 18:17:47 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/memory-failure: send SIGBUS(BUS_MCEERR_AR) only to current thread 2020-06-11 18:17:47 -07:00
net NFS Client Updates for Linux 5.8 2020-06-11 12:22:41 -07:00
samples Kbuild updates for v5.8 2020-06-06 12:00:25 -07:00
scripts Merge branch 'akpm' (patches from Andrew) 2020-06-11 13:25:53 -07:00
security overlayfs update for 5.8 2020-06-09 15:40:50 -07:00
sound sound fixes for 5.8-rc1 2020-06-11 12:38:11 -07:00
tools Merge branch 'akpm' (patches from Andrew) 2020-06-11 13:25:53 -07:00
usr bpfilter: match bit size of bpfilter_umh to that of the kernel 2020-05-17 18:52:01 +09:00
virt mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
.clang-format block: add bio_for_each_bvec_all() 2020-05-25 11:25:24 +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 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 - qcom : 2020-06-11 12:42:14 -07:00
Makefile Kbuild updates for v5.8 2020-06-06 12:00:25 -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.