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Mark Rutland bbb14cc996 arm64: ftrace: fix branch range checks
[ Upstream commit 3eefdf9d1e ]

The branch range checks in ftrace_make_call() and ftrace_make_nop() are
incorrect, erroneously permitting a forwards branch of 128M and
erroneously rejecting a backwards branch of 128M.

This is because both functions calculate the offset backwards,
calculating the offset *from* the target *to* the branch, rather than
the other way around as the later comparisons expect.

If an out-of-range branch were erroeously permitted, this would later be
rejected by aarch64_insn_gen_branch_imm() as branch_imm_common() checks
the bounds correctly, resulting in warnings and the placement of a BRK
instruction. Note that this can only happen for a forwards branch of
exactly 128M, and so the caller would need to be exactly 128M bytes
below the relevant ftrace trampoline.

If an in-range branch were erroeously rejected, then:

* For modules when CONFIG_ARM64_MODULE_PLTS=y, this would result in the
  use of a PLT entry, which is benign.

  Note that this is the common case, as this is selected by
  CONFIG_RANDOMIZE_BASE (and therefore RANDOMIZE_MODULE_REGION_FULL),
  which distributions typically seelct. This is also selected by
  CONFIG_ARM64_ERRATUM_843419.

* For modules when CONFIG_ARM64_MODULE_PLTS=n, this would result in
  internal ftrace failures.

* For core kernel text, this would result in internal ftrace failues.

  Note that for this to happen, the kernel text would need to be at
  least 128M bytes in size, and typical configurations are smaller tha
  this.

Fix this by calculating the offset *from* the branch *to* the target in
both functions.

Fixes: f8af0b364e ("arm64: ftrace: don't validate branch via PLT in ftrace_make_nop()")
Fixes: e71a4e1beb ("arm64: ftrace: add support for far branches to dynamic ftrace")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Will Deacon <will@kernel.org>
Tested-by: "Ivan T. Ivanov" <iivanov@suse.de>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220614080944.1349146-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-06-25 11:46:44 +02:00
arch arm64: ftrace: fix branch range checks 2022-06-25 11:46:44 +02:00
block block-map: add __GFP_ZERO flag for alloc_page in function bio_copy_kern 2022-06-06 08:20:57 +02:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-22 11:45:19 +02:00
crypto crypto: drbg - make reseeding from get_random_bytes() synchronous 2022-06-25 11:46:41 +02:00
Documentation random: fix sysctl documentation nits 2022-06-25 11:46:38 +02:00
drivers net: bgmac: Fix an erroneous kfree() in bgmac_remove() 2022-06-25 11:46:44 +02:00
firmware Fix built-in early-load Intel microcode alignment 2020-01-23 08:20:30 +01:00
fs pNFS: Don't keep retrying if the server replied NFS4ERR_LAYOUTUNAVAILABLE 2022-06-25 11:46:43 +02:00
include random: mark bootloader randomness code as __init 2022-06-25 11:46:42 +02:00
init random: handle latent entropy and command line from random_init() 2022-06-25 11:46:40 +02:00
ipc ipc: WARN if trying to remove ipc object which is absent 2021-12-08 08:46:53 +01:00
kernel timekeeping: Add raw clock fallback for random_get_entropy() 2022-06-25 11:46:38 +02:00
lib random: remove ratelimiting for in-kernel unseeded randomness 2022-06-25 11:46:40 +02:00
mm random: move randomize_page() into mm where it belongs 2022-06-25 11:46:40 +02:00
net ipv6: Fix signed integer overflow in l2tp_ip6_sendmsg 2022-06-25 11:46:43 +02:00
samples samples/kretprobes: Fix return value if register_kretprobe() failed 2021-11-26 11:40:31 +01:00
scripts modpost: fix undefined behavior of is_arm_mapping_symbol() 2022-06-14 16:54:00 +02:00
security Fix incorrect type in assignment of ipv6 port for audit 2022-04-20 09:08:21 +02:00
sound ASoC: wm8962: Fix suspend while playing music 2022-06-25 11:46:42 +02:00
tools perf c2c: Fix sorting in percent_rmt_hitm_cmp() 2022-06-14 16:53:57 +02:00
usr initramfs: restore default compression behavior 2020-04-13 10:34:19 +02:00
virt KVM: Prevent module exit until all VMs are freed 2022-04-20 09:08:24 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS MAINTAINERS: co-maintain random.c 2022-06-25 11:46:29 +02:00
Makefile Linux 4.14.284 2022-06-16 13:01:55 +02:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.