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Filename Latest commit message Latest commit date
Mark Rutland fb775ee3cf arm64: ftrace: fix branch range checks
[ Upstream commit 3eefdf9d1e406f3da47470b2854347009ffcb6fa ]

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>
2022-06-22 14:11:22 +02:00
arch arm64: ftrace: fix branch range checks 2022-06-22 14:11:22 +02:00
block block: fix bio_clone_blkg_association() to associate with proper blkcg_gq 2022-06-14 18:11:50 +02:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:47:29 +02:00
crypto crypto: drbg - make reseeding from get_random_bytes() synchronous 2022-06-22 14:11:18 +02:00
Documentation random: fix sysctl documentation nits 2022-06-22 14:11:14 +02:00
drivers net: bgmac: Fix an erroneous kfree() in bgmac_remove() 2022-06-22 14:11:22 +02:00
fs pNFS: Don't keep retrying if the server replied NFS4ERR_LAYOUTUNAVAILABLE 2022-06-22 14:11:21 +02:00
include random: mark bootloader randomness code as __init 2022-06-22 14:11:19 +02:00
init random: handle latent entropy and command line from random_init() 2022-06-22 14:11:17 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-14 18:11:41 +02:00
kernel dma-debug: make things less spammy under memory pressure 2022-06-22 14:11:19 +02:00
lib random: remove ratelimiting for in-kernel unseeded randomness 2022-06-22 14:11:17 +02:00
LICENSES
mm random: move randomize_page() into mm where it belongs 2022-06-22 14:11:17 +02:00
net ipv6: Fix signed integer overflow in l2tp_ip6_sendmsg 2022-06-22 14:11:21 +02:00
samples samples/kretprobes: Fix return value if register_kretprobe() failed 2021-11-17 09:48:39 +01:00
scripts scripts/gdb: change kernel config dumping method 2022-06-14 18:12:02 +02:00
security efi: Do not import certificates from UEFI Secure Boot for T2 Macs 2022-06-14 18:11:44 +02:00
sound ALSA: hda/realtek - Add HW8326 support 2022-06-22 14:11:21 +02:00
tools netfilter: nat: really support inet nat without l3 address 2022-06-14 18:11:57 +02:00
usr
virt KVM: Prevent module exit until all VMs are freed 2022-04-15 14:18:27 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: co-maintain random.c 2022-06-22 14:11:05 +02:00
Makefile Linux 5.4.199 2022-06-16 13:23:32 +02:00
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.