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Jason A. Donenfeld d7bf7f3b81 random: always mix cycle counter in add_latent_entropy()
add_latent_entropy() is called every time a process forks, in
kernel_clone(). This in turn calls add_device_randomness() using the
latent entropy global state. add_device_randomness() does two things:

   2) Mixes into the input pool the latent entropy argument passed; and
   1) Mixes in a cycle counter, a sort of measurement of when the event
      took place, the high precision bits of which are presumably
      difficult to predict.

(2) is impossible without CONFIG_GCC_PLUGIN_LATENT_ENTROPY=y. But (1) is
always possible. However, currently CONFIG_GCC_PLUGIN_LATENT_ENTROPY=n
disables both (1) and (2), instead of just (2).

This commit causes the CONFIG_GCC_PLUGIN_LATENT_ENTROPY=n case to still
do (1) by passing NULL (len 0) to add_device_randomness() when add_latent_
entropy() is called.

Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Emese Revfy <re.emese@gmail.com>
Fixes: 38addce8b6 ("gcc-plugins: Add latent_entropy plugin")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-11-18 02:18:10 +01:00
Documentation random: use random.trust_{bootloader,cpu} command line option only 2022-11-18 02:18:10 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch random: remove early archrandom abstraction 2022-11-18 02:18:10 +01:00
block block-6.1-2022-11-11 2022-11-11 14:08:30 -08:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto treewide: use get_random_u32_inclusive() when possible 2022-11-18 02:18:02 +01:00
drivers hw_random: use add_hwgenerator_randomness() for early entropy 2022-11-18 02:18:10 +01:00
fs treewide: use get_random_u32_inclusive() when possible 2022-11-18 02:18:02 +01:00
include random: always mix cycle counter in add_latent_entropy() 2022-11-18 02:18:10 +01:00
init init: Kconfig: fix spelling mistake "satify" -> "satisfy" 2022-10-20 21:27:22 -07:00
io_uring io_uring/poll: lockdep annote io_poll_req_insert_locked 2022-11-11 09:59:27 -07:00
ipc ipc/msg.c: fix percpu_counter use after free 2022-10-28 13:37:22 -07:00
kernel stackprotector: move get_random_canary() into stackprotector.h 2022-11-18 02:18:10 +01:00
lib treewide: use get_random_u32_inclusive() when possible 2022-11-18 02:18:02 +01:00
mm treewide: use get_random_u32_inclusive() when possible 2022-11-18 02:18:02 +01:00
net treewide: use get_random_u32_inclusive() when possible 2022-11-18 02:18:02 +01:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples VFIO updates for v6.1-rc1 2022-10-12 14:46:48 -07:00
scripts s390 updates for 6.1-rc5 2022-11-11 11:49:20 -08:00
security lsm/stable-6.1 PR 20221031 2022-10-31 12:09:42 -07:00
sound ALSA: memalloc: Try dma_alloc_noncontiguous() at first 2022-11-12 09:48:51 +01:00
tools random: use random.trust_{bootloader,cpu} command line option only 2022-11-18 02:18:10 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge tag 'kvmarm-fixes-6.1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD 2022-11-06 03:30:49 -05:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.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 mailmap: update email for Qais Yousef 2022-10-20 21:27:21 -07:00
.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: Move Vivien to CREDITS 2022-11-10 13:53:53 -08:00
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 hyperv-fixes for v6.1-rc5 2022-11-11 09:24:03 -08:00
Makefile Linux 6.1-rc5 2022-11-13 13:12:55 -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.