linux-toradex.git/include/linux/fortify-string.h, branch v6.4-rc1

fortify: Use __builtin_dynamic_object_size() when available

2023-01-05T20:08:29+00:00

Since the commits starting with c37495d6254c ("slab: add __alloc_size
attributes for better bounds checking"), the compilers have runtime
allocation size hints available in some places. This was immediately
available to CONFIG_UBSAN_BOUNDS, but CONFIG_FORTIFY_SOURCE needed
updating to explicitly make use of the hints via the associated
__builtin_dynamic_object_size() helper. Detect and use the builtin when
it is available, increasing the accuracy of the mitigation. When runtime
sizes are not available, __builtin_dynamic_object_size() falls back to
__builtin_object_size(), leaving the existing bounds checking unchanged.

Additionally update the VMALLOC_LINEAR_OVERFLOW LKDTM test to make the
hint invisible, otherwise the architectural defense is not exercised
(the buffer overflow is detected in the memset() rather than when it
crosses the edge of the allocation).

Cc: Arnd Bergmann 
Cc: Greg Kroah-Hartman 
Cc: Nick Desaulniers 
Cc: Nathan Chancellor 
Cc: Tom Rix 
Cc: linux-hardening@vger.kernel.org
Cc: llvm@lists.linux.dev
Reviewed-by: Miguel Ojeda  # include/linux/compiler_attributes.h
Signed-off-by: Kees Cook

Merge tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2022-12-14T20:20:00+00:00

Pull kernel hardening updates from Kees Cook:

 - Convert flexible array members, fix -Wstringop-overflow warnings, and
   fix KCFI function type mismatches that went ignored by maintainers
   (Gustavo A. R. Silva, Nathan Chancellor, Kees Cook)

 - Remove the remaining side-effect users of ksize() by converting
   dma-buf, btrfs, and coredump to using kmalloc_size_roundup(), add
   more __alloc_size attributes, and introduce full testing of all
   allocator functions. Finally remove the ksize() side-effect so that
   each allocation-aware checker can finally behave without exceptions

 - Introduce oops_limit (default 10,000) and warn_limit (default off) to
   provide greater granularity of control for panic_on_oops and
   panic_on_warn (Jann Horn, Kees Cook)

 - Introduce overflows_type() and castable_to_type() helpers for cleaner
   overflow checking

 - Improve code generation for strscpy() and update str*() kern-doc

 - Convert strscpy and sigphash tests to KUnit, and expand memcpy tests

 - Always use a non-NULL argument for prepare_kernel_cred()

 - Disable structleak plugin in FORTIFY KUnit test (Anders Roxell)

 - Adjust orphan linker section checking to respect CONFIG_WERROR (Xin
   Li)

 - Make sure siginfo is cleared for forced SIGKILL (haifeng.xu)

 - Fix um vs FORTIFY warnings for always-NULL arguments

* tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (31 commits)
  ksmbd: replace one-element arrays with flexible-array members
  hpet: Replace one-element array with flexible-array member
  um: virt-pci: Avoid GCC non-NULL warning
  signal: Initialize the info in ksignal
  lib: fortify_kunit: build without structleak plugin
  panic: Expose "warn_count" to sysfs
  panic: Introduce warn_limit
  panic: Consolidate open-coded panic_on_warn checks
  exit: Allow oops_limit to be disabled
  exit: Expose "oops_count" to sysfs
  exit: Put an upper limit on how often we can oops
  panic: Separate sysctl logic from CONFIG_SMP
  mm/pgtable: Fix multiple -Wstringop-overflow warnings
  mm: Make ksize() a reporting-only function
  kunit/fortify: Validate __alloc_size attribute results
  drm/sti: Fix return type of sti_{dvo,hda,hdmi}_connector_mode_valid()
  drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid()
  driver core: Add __alloc_size hint to devm allocators
  overflow: Introduce overflows_type() and castable_to_type()
  coredump: Proactively round up to kmalloc bucket size
  ...

Merge tag 'hardening-v6.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2022-11-04T21:46:45+00:00

Pull hardening fix from Kees Cook:

 - Correctly report struct member size on memcpy overflow (Kees Cook)

* tag 'hardening-v6.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  fortify: Capture __bos() results in const temp vars

fortify: Do not cast to "unsigned char"

2022-11-01T17:04:52+00:00

Do not cast to "unsigned char", as this needlessly creates type problems
when attempting builds without -Wno-pointer-sign[1]. The intent of the
cast is to drop possible "const" types.

[1] https://lore.kernel.org/lkml/CAHk-=wgz3Uba8w7kdXhsqR1qvfemYL+OFQdefJnkeqXG8qZ_pA@mail.gmail.com/

Suggested-by: Linus Torvalds 
Fixes: 3009f891bb9f ("fortify: Allow strlen() and strnlen() to pass compile-time known lengths")
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook

fortify: Short-circuit known-safe calls to strscpy()

2022-11-01T17:04:52+00:00

Replacing compile-time safe calls of strcpy()-related functions with
strscpy() was always calling the full strscpy() logic when a builtin
would be better. For example:

	char buf[16];
	strcpy(buf, "yes");

would reduce to __builtin_memcpy(buf, "yes", 4), but not if it was:

	strscpy(buf, yes, sizeof(buf));

Fix this by checking if all sizes are known at compile-time.

Cc: linux-hardening@vger.kernel.org
Tested-by: Nathan Chancellor 
Signed-off-by: Kees Cook

string: Add __realloc_size hint to kmemdup()

2022-11-01T17:04:51+00:00

Add __realloc_size() hint to kmemdup() so the compiler can reason about
the length of the returned buffer. (These must not use __alloc_size,
since those include __malloc which says the contents aren't defined[1]).

[1] https://lore.kernel.org/linux-hardening/d199c2af-06af-8a50-a6a1-00eefa0b67b4@prevas.dk/

Cc: Rasmus Villemoes 
Cc: Guenter Roeck 
Cc: Andy Shevchenko 
Cc: Paolo Abeni 
Cc: Geert Uytterhoeven 
Signed-off-by: Kees Cook

string: Rewrite and add more kern-doc for the str*() functions

2022-10-28T23:07:57+00:00

While there were varying degrees of kern-doc for various str*()-family
functions, many needed updating and clarification, or to just be
entirely written. Update (and relocate) existing kern-doc and add missing
functions, sadly shaking my head at how many times I have written "Do
not use this function". Include the results in the core kernel API doc.

Cc: Bagas Sanjaya 
Cc: Andy Shevchenko 
Cc: Rasmus Villemoes 
Cc: Andrew Morton 
Cc: linux-hardening@vger.kernel.org
Tested-by: Akira Yokosawa 
Link: https://lore.kernel.org/lkml/9b0cf584-01b3-3013-b800-1ef59fe82476@gmail.com
Signed-off-by: Kees Cook

fortify: Capture __bos() results in const temp vars

2022-10-28T23:07:01+00:00

In two recent run-time memcpy() bound checking bug reports (NFS[1] and
JFS[2]), the _detection_ was working correctly (in the sense that the
requested copy size was larger than the destination field size), but
the _warning text_ was showing the destination field size as SIZE_MAX
("unknown size"). This should be impossible, since the detection function
will explicitly give up if the destination field size is unknown. For
example, the JFS warning was:

  memcpy: detected field-spanning write (size 132) of single field "ip->i_link" at fs/jfs/namei.c:950 (size 18446744073709551615)

Other cases of this warning (e.g.[3]) have reported correctly,
and the reproducer only happens under GCC (at least 10.2 and 12.1),
so this currently appears to be a GCC bug. Explicitly capturing the
__builtin_object_size() results in const temporary variables fixes the
report. For example, the JFS reproducer now correctly reports the field
size (128):

  memcpy: detected field-spanning write (size 132) of single field "ip->i_link" at fs/jfs/namei.c:950 (size 128)

Examination of the .text delta (which is otherwise identical), shows
the literal value used in the report changing:

-     mov    $0xffffffffffffffff,%rcx
+     mov    $0x80,%ecx

[1] https://lore.kernel.org/lkml/Y0zEzZwhOxTDcBTB@codemonkey.org.uk/
[2] https://syzkaller.appspot.com/bug?id=23d613df5259b977dac1696bec77f61a85890e3d
[3] https://lore.kernel.org/all/202210110948.26b43120-yujie.liu@intel.com/

Cc: "Dr. David Alan Gilbert" 
Cc: llvm@lists.linux.dev
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook

x86: fortify: kmsan: fix KMSAN fortify builds

2022-10-28T20:37:23+00:00

Ensure that KMSAN builds replace memset/memcpy/memmove calls with the
respective __msan_XXX functions, and that none of the macros are redefined
twice.  This should allow building kernel with both CONFIG_KMSAN and
CONFIG_FORTIFY_SOURCE.

Link: https://lkml.kernel.org/r/20221024212144.2852069-5-glider@google.com
Link: https://github.com/google/kmsan/issues/89
Signed-off-by: Alexander Potapenko 
Reported-by: Tamas K Lengyel 
Cc: Nathan Chancellor 
Cc: Nick Desaulniers 
Cc: Kees Cook 
Signed-off-by: Andrew Morton

Merge tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-10-11T00:53:04+00:00

Pull MM updates from Andrew Morton:

- Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any
negative reports (or any positive ones, come to that).

- Also the Maple Tree from Liam Howlett. An overlapping range-based
tree for vmas. It it apparently slightly more efficient in its own
right, but is mainly targeted at enabling work to reduce mmap_lock
contention.

Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.

Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
at [1]. This has yet to be addressed due to Liam's unfortunately
timed vacation. He is now back and we'll get this fixed up.

- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down
to the single bit level.

KMSAN keeps finding bugs. New ones, as well as the legacy ones.

- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.

- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
support file/shmem-backed pages.

- userfaultfd updates from Axel Rasmussen

- zsmalloc cleanups from Alexey Romanov

- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
memory-failure

- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.

- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.

- memcg cleanups from Kairui Song.

- memcg fixes and cleanups from Johannes Weiner.

- Vishal Moola provides more folio conversions

- Zhang Yi removed ll_rw_block() :(

- migration enhancements from Peter Xu

- migration error-path bugfixes from Huang Ying

- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.

- vma merging improvements from Jakub Matěn.

- NUMA hinting cleanups from David Hildenbrand.

- xu xin added aditional userspace visibility into KSM merging
activity.

- THP & KSM code consolidation from Qi Zheng.

- more folio work from Matthew Wilcox.

- KASAN updates from Andrey Konovalov.

- DAMON cleanups from Kaixu Xia.

- DAMON work from SeongJae Park: fixes, cleanups.

- hugetlb sysfs cleanups from Muchun Song.

- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.

Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1]

* tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits)
hugetlb: allocate vma lock for all sharable vmas
hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
hugetlb: fix vma lock handling during split vma and range unmapping
mglru: mm/vmscan.c: fix imprecise comments
mm/mglru: don't sync disk for each aging cycle
mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
mm: memcontrol: use do_memsw_account() in a few more places
mm: memcontrol: deprecate swapaccounting=0 mode
mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
mm/secretmem: remove reduntant return value
mm/hugetlb: add available_huge_pages() func
mm: remove unused inline functions from include/linux/mm_inline.h
selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory
selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd
selftests/vm: add thp collapse shmem testing
selftests/vm: add thp collapse file and tmpfs testing
selftests/vm: modularize thp collapse memory operations
selftests/vm: dedup THP helpers
mm/khugepaged: add tracepoint to hpage_collapse_scan_file()
mm/madvise: add file and shmem support to MADV_COLLAPSE
...