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Kees Cook 6db1208bf9 randomize_kstack: Remove non-functional per-arch entropy filtering
An unintended consequence of commit 9c573cd313 ("randomize_kstack:
Improve entropy diffusion") was that the per-architecture entropy size
filtering reduced how many bits were being added to the mix, rather than
how many bits were being used during the offsetting. All architectures
fell back to the existing default of 0x3FF (10 bits), which will consume
at most 1KiB of stack space. It seems that this is working just fine,
so let's avoid the confusion and update everything to use the default.

The prior intent of the per-architecture limits were:

  arm64: capped at 0x1FF (9 bits), 5 bits effective
  powerpc: uncapped (10 bits), 6 or 7 bits effective
  riscv: uncapped (10 bits), 6 bits effective
  x86: capped at 0xFF (8 bits), 5 (x86_64) or 6 (ia32) bits effective
  s390: capped at 0xFF (8 bits), undocumented effective entropy

Current discussion has led to just dropping the original per-architecture
filters. The additional entropy appears to be safe for arm64, x86,
and s390. Quoting Arnd, "There is no point pretending that 15.75KB is
somehow safe to use while 15.00KB is not."

Co-developed-by: Yuntao Liu <liuyuntao12@huawei.com>
Signed-off-by: Yuntao Liu <liuyuntao12@huawei.com>
Fixes: 9c573cd313 ("randomize_kstack: Improve entropy diffusion")
Link: https://lore.kernel.org/r/20240617133721.377540-1-liuyuntao12@huawei.com
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # s390
Link: https://lore.kernel.org/r/20240619214711.work.953-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2024-06-28 08:54:56 -07:00
arch randomize_kstack: Remove non-functional per-arch entropy filtering 2024-06-28 08:54:56 -07:00
block blk-throttle: Fix incorrect display of io.max 2024-05-30 19:44:29 -06:00
certs kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
crypto This push fixes a bug in the new ecc P521 code as well as a buggy 2024-05-20 08:47:54 -07:00
Documentation dma-mapping fixes for Linux 6.10 2024-05-31 12:14:55 -07:00
drivers mm/util: Swap kmemdup_array() arguments 2024-06-06 08:55:20 -07:00
fs 2 small smb3 fixes 2024-06-01 14:35:57 -07:00
include mm/util: Swap kmemdup_array() arguments 2024-06-06 08:55:20 -07:00
init Driver core changes for 6.10-rc1 2024-05-22 12:13:40 -07:00
io_uring io_uring/net: assign kmsg inq/flags before buffer selection 2024-05-30 14:04:37 -06:00
ipc Mainly singleton patches, documented in their respective changelogs. 2024-05-19 14:02:03 -07:00
kernel Kbuild fixes for v6.10 2024-06-01 09:33:55 -07:00
lib string: kunit: add missing MODULE_DESCRIPTION() macros 2024-06-28 08:54:55 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/util: Swap kmemdup_array() arguments 2024-06-06 08:55:20 -07:00
net Including fixes from bpf and netfilter. 2024-05-30 08:33:04 -07:00
rust LoongArch changes for v6.10 2024-05-22 09:43:07 -07:00
samples tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
scripts dt-bindings: kbuild: Fix dt_binding_check on unconfigured build 2024-05-30 01:15:58 +09:00
security yama: document function parameter 2024-06-06 11:40:28 -07:00
sound ALSA: seq: ump: Fix swapped song position pointer data 2024-05-31 09:51:44 +02:00
tools Landlock fix for v6.10-rc2 2024-06-01 08:28:24 -07:00
usr kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
virt The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: create a list of all built DTB files 2024-02-19 18:20:39 +09:00
.mailmap mailmap: update entry for Kees Cook 2024-05-31 08:58:36 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: Drop Gustavo Pimentel as PCI DWC Maintainer 2024-03-27 13:41:02 -05:00
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 MAINTAINERS: Update entries for Kees Cook 2024-06-17 11:14:06 -07:00
Makefile Linux 6.10-rc2 2024-06-02 15:44:56 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.