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Florent Revest 488ffc0cac x86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodes 
commit e3e89178a9 upstream.

Currently, load_microcode_amd() iterates over all NUMA nodes, retrieves their
CPU masks and unconditionally accesses per-CPU data for the first CPU of each
mask.

According to Documentation/admin-guide/mm/numaperf.rst:

  "Some memory may share the same node as a CPU, and others are provided as
  memory only nodes."

Therefore, some node CPU masks may be empty and wouldn't have a "first CPU".

On a machine with far memory (and therefore CPU-less NUMA nodes):
- cpumask_of_node(nid) is 0
- cpumask_first(0) is CONFIG_NR_CPUS
- cpu_data(CONFIG_NR_CPUS) accesses the cpu_info per-CPU array at an
  index that is 1 out of bounds

This does not have any security implications since flashing microcode is
a privileged operation but I believe this has reliability implications by
potentially corrupting memory while flashing a microcode update.

When booting with CONFIG_UBSAN_BOUNDS=y on an AMD machine that flashes
a microcode update. I get the following splat:

  UBSAN: array-index-out-of-bounds in arch/x86/kernel/cpu/microcode/amd.c:X:Y
  index 512 is out of range for type 'unsigned long[512]'
  [...]
  Call Trace:
   dump_stack
   __ubsan_handle_out_of_bounds
   load_microcode_amd
   request_microcode_amd
   reload_store
   kernfs_fop_write_iter
   vfs_write
   ksys_write
   do_syscall_64
   entry_SYSCALL_64_after_hwframe

Change the loop to go over only NUMA nodes which have CPUs before determining
whether the first CPU on the respective node needs microcode update.

  [ bp: Massage commit message, fix typo. ]

Fixes: 7ff6edf4fe ("x86/microcode/AMD: Fix mixed steppings support")
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250310144243.861978-1-revest@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-03-22 12:54:23 -07:00
arch x86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodes 2025-03-22 12:54:23 -07:00
block block: fix 'kmem_cache of name 'bio-108' already exists' 2025-03-22 12:54:21 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: api - Fix boot-up self-test race 2025-02-08 09:57:28 +01:00
Documentation rust: remove leftover mentions of the alloc crate 2025-03-22 12:54:23 -07:00
drivers USB: serial: option: match on interface class for Telit FN990B 2025-03-22 12:54:22 -07:00
fs cifs: Throw -EOPNOTSUPP error on unsupported reparse point type from parse_reparse_point() 2025-03-22 12:54:21 -07:00
include fuse: don't truncate cached, mutated symlink 2025-03-22 12:54:20 -07:00
init rust: Disallow BTF generation with Rust + LTO 2025-03-22 12:54:23 -07:00
io_uring io-wq: backoff when retrying worker creation 2025-03-22 12:54:19 -07:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-05 14:03:02 +01:00
kernel vhost: return task creation error instead of NULL 2025-03-22 12:54:21 -07:00
lib rcuref: Plug slowpath race in rcuref_put() 2025-03-07 18:25:43 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm userfaultfd: fix PTE unmapping stack-allocated PTE copies 2025-03-22 12:54:09 -07:00
net net: Handle napi_schedule() calls from non-interrupt 2025-03-22 12:54:21 -07:00
rust rust: init: fix Zeroable implementation for Option<NonNull<T>> and Option<KBox<T>> 2025-03-22 12:54:23 -07:00
samples rust: treewide: switch to the kernel Vec type 2025-03-13 13:01:46 +01:00
scripts rust: remove leftover mentions of the alloc crate 2025-03-22 12:54:23 -07:00
security ima: Reset IMA_NONACTION_RULE_FLAGS after post_setattr 2025-03-07 18:25:44 +01:00
sound ASoC: SOF: Intel: don't check number of sdw links when set dmic_fixup 2025-03-22 12:54:20 -07:00
tools ASoC: dapm-graph: set fill colour of turned on nodes 2025-03-22 12:54:20 -07:00
usr kbuild: hdrcheck: fix cross build with clang 2025-03-13 13:02:18 +01:00
virt KVM: x86: switch hugepage recovery thread to vhost_task 2024-12-05 14:02:43 +01:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: enable Clippy's check-private-items 2025-03-13 13:01:42 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.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 rust: introduce .clippy.toml 2025-03-13 13:01:42 +01:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.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: Remove self from DSA entry 2024-11-03 12:52:38 -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 MAINTAINERS: add entry for the Rust alloc module 2025-03-13 13:01:47 +01:00
Makefile Linux 6.12.19 2025-03-13 13:02:20 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -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 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.