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Matthew Wilcox (Oracle) 837f5cb7be x86/mm: Clear _PAGE_DIRTY for kernel mappings when we clear _PAGE_RW 
[ Upstream commit c1fcf41cf3 ]

The bit pattern of _PAGE_DIRTY set and _PAGE_RW clear is used to mark
shadow stacks.  This is currently checked for in mk_pte() but not
pfn_pte().  If we add the check to pfn_pte(), it catches vfree()
calling set_direct_map_invalid_noflush() which calls
__change_page_attr() which loads the old protection bits from the
PTE, clears the specified bits and uses pfn_pte() to construct the
new PTE.

We should, therefore, for kernel mappings, clear the _PAGE_DIRTY bit
consistently whenever we clear _PAGE_RW.  I opted to do it in the
callers in case we want to use __change_page_attr() to create shadow
stacks inside the kernel at some point in the future.  Arguably, we
might also want to clear _PAGE_ACCESSED here.

Note that the 3 functions involved:

  __set_pages_np()
  kernel_map_pages_in_pgd()
  kernel_unmap_pages_in_pgd()

Only ever manipulate non-swappable kernel mappings, so maintaining
the DIRTY:1|RW:0 special pattern for shadow stacks and DIRTY:0
pattern for non-shadow-stack entries can be maintained consistently
and doesn't result in the unintended clearing of a live dirty bit
that could corrupt (destroy) dirty bit information for user mappings.

Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/174051422675.10177.13226545170101706336.tip-bot2@tip-bot2
Closes: https://lore.kernel.org/oe-lkp/202502241646.719f4651-lkp@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-04-20 10:15:11 +02:00
arch x86/mm: Clear _PAGE_DIRTY for kernel mappings when we clear _PAGE_RW 2025-04-20 10:15:11 +02:00
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 larval relookup type and mask 2025-04-10 14:39:20 +02:00
Documentation dt-bindings: vendor-prefixes: add GOcontroll 2025-04-10 14:39:13 +02:00
drivers iommu/mediatek: Fix NULL pointer deference in mtk_iommu_device_group 2025-04-20 10:15:09 +02:00
fs umount: Allow superblock owners to force umount 2025-04-20 10:15:10 +02:00
include perf: Fix hang while freeing sigtrap event 2025-04-20 10:15:10 +02:00
init ARM: 9443/1: Require linker to support KEEP within OVERLAY for DCE 2025-04-10 14:39:40 +02:00
io_uring io_uring/net: fix sendzc double notif flush 2025-03-28 22:03:32 +01:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-05 14:03:02 +01:00
kernel perf: Fix hang while freeing sigtrap event 2025-04-20 10:15:10 +02:00
lib rust: fix signature of rust_fmt_argument 2025-04-10 14:39:20 +02:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm: zswap: fix crypto_free_acomp() deadlock in zswap_cpu_comp_dead() 2025-04-10 14:39:40 +02:00
net nft_set_pipapo: fix incorrect avx2 match of 5th field octet 2025-04-20 10:15:09 +02:00
rust rust: Fix enabling Rust and building with GCC for LoongArch 2025-04-10 14:39:36 +02:00
samples rust: treewide: switch to the kernel Vec type 2025-03-13 13:01:46 +01:00
scripts kbuild: deb-pkg: don't set KBUILD_BUILD_VERSION unconditionally 2025-04-10 14:39:35 +02:00
security smack: ipv4/ipv6: tcp/dccp/sctp: fix incorrect child socket label 2025-04-10 14:39:10 +02:00
sound ASoC: Intel: adl: add 2xrt1316 audio configuration 2025-04-20 10:15:04 +02:00
tools pm: cpupower: bench: Prevent NULL dereference on malloc failure 2025-04-20 10:15:10 +02:00
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 6.12.23 2025-04-10 14:39:41 +02:00
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.