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Catalin Marinas f620d66af3 arm64: mte: Do not flag the zero page as PG_mte_tagged
Commit 68d54ceeec ("arm64: mte: Allow PTRACE_PEEKMTETAGS access to the
zero page") attempted to fix ptrace() reading of tags from the zero page
by marking it as PG_mte_tagged during cpu_enable_mte(). The same commit
also changed the ptrace() tag access permission check to the VM_MTE vma
flag while turning the page flag test into a WARN_ON_ONCE().

Attempting to set the PG_mte_tagged flag early with
CONFIG_DEFERRED_STRUCT_PAGE_INIT enabled may either hang (after commit
d77e59a8fc "arm64: mte: Lock a page for MTE tag initialisation") or
have the flags cleared later during page_alloc_init_late(). In addition,
pages_identical() -> memcmp_pages() will reject any comparison with the
zero page as it is marked as tagged.

Partially revert the above commit to avoid setting PG_mte_tagged on the
zero page. Update the __access_remote_tags() warning on untagged pages
to ignore the zero page since it is known to have the tags initialised.

Note that all user mapping of the zero page are marked as pte_special().
The arm64 set_pte_at() will not call mte_sync_tags() on such pages, so
PG_mte_tagged will remain cleared.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Fixes: 68d54ceeec ("arm64: mte: Allow PTRACE_PEEKMTETAGS access to the zero page")
Reported-by: Gergely Kovacs <Gergely.Kovacs2@arm.com>
Cc: stable@vger.kernel.org # 5.10.x
Cc: Will Deacon <will@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Lance Yang <lance.yang@linux.dev>
Acked-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: David Hildenbrand <david@redhat.com>
Tested-by: Lance Yang <lance.yang@linux.dev>
Signed-off-by: Will Deacon <will@kernel.org>
History 2025-10-03 15:27:34 +01:00
arch arm64: mte: Do not flag the zero page as PG_mte_tagged 2025-10-03 15:27:34 +01:00
block block-6.17-20250808 2025-08-09 08:47:28 +03:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto Significant patch series in this pull request: 2025-08-03 16:23:09 -07:00
Documentation docs: perf: Fujitsu: Fix htmldocs build warnings and errors 2025-09-26 14:34:35 +01:00
drivers drivers/perf: hisi: Add tt_core_deprecated for compatibility 2025-09-25 13:51:59 +01:00
fs NFS client updates for Linux 6.17 2025-08-09 07:20:44 +03:00
include arm64: Enable permission change on arm64 kernel block mappings 2025-09-18 21:36:37 +01:00
init Significant patch series in this pull request: 2025-08-03 16:23:09 -07:00
io_uring io_uring/memmap: cast nr_pages to size_t before shifting 2025-08-08 06:35:14 -06:00
ipc vfs-6.17-rc1.mmap_prepare 2025-07-28 13:43:25 -07:00
kernel Merge branch 'for-next/uprobes' into for-next/core 2025-09-24 16:35:06 +01:00
lib block-6.17-20250808 2025-08-09 08:47:28 +03:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm arm64: Enable permission change on arm64 kernel block mappings 2025-09-18 21:36:37 +01:00
net NFS client updates for Linux 6.17 2025-08-09 07:20:44 +03:00
rust Rust changes for v6.17 2025-08-03 13:49:10 -07:00
samples Significant patch series in this pull request: 2025-08-03 16:23:09 -07:00
scripts Kbuild updates for v6.17 2025-08-06 07:32:52 +03:00
security + Features 2025-08-04 08:17:28 -07:00
sound gpio updates for v6.17-rc1 2025-08-09 08:15:43 +03:00
tools Merge branch 'for-next/selftests' into for-next/core 2025-09-24 16:34:56 +01:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt Merge tag 'kvm-x86-no_assignment-6.17' of https://github.com/kvm-x86/linux into HEAD 2025-07-29 08:36:42 -04:00
.clang-format Linux 6.15-rc5 2025-05-06 16:39:25 +10:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.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 MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore gitignore: allow .pylintrc to be tracked 2025-07-02 17:10:04 -06:00
.mailmap Significant patch series in this pull request: 2025-08-03 16:23:09 -07:00
.pylintrc docs: add a .pylintrc file with sys path for docs scripts 2025-04-09 12:10:33 -06:00
.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 Kbuild updates for v6.17 2025-08-06 07:32:52 +03:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS MAINTAINERS: Remove myself from HiSilicon PMU maintainers 2025-09-18 14:54:29 +01:00
Makefile Linux 6.17-rc1 2025-08-10 19:41:16 +03:00
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.