[GIT PULL] ffs-const update for v6.18-rc1
From: Kees Cook
Date: Mon Sep 29 2025 - 15:02:45 EST
Hi Linus,
Please pull this ffs() attribute-const update for v6.18-rc1. While
working on various hardening refactoring a while back we encountered
inconsistencies in the application of __attribute_const__ on the ffs()
family of functions. This series fixes this across all archs and adds
KUnit tests. Notably, this found a theoretical underflow in PCI (also
fixed here) and uncovered an inefficiency in ARC (fixed in the ARC
arch PR). I kept the series separate from the general hardening PR since
it is a stand-alone "topic".
Thanks!
-Kees
The following changes since commit c17b750b3ad9f45f2b6f7e6f7f4679844244f0b9:
Linux 6.17-rc2 (2025-08-17 15:22:10 -0700)
are available in the Git repository at:
https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git tags/ffs-const-v6.18-rc1
for you to fetch changes up to 95719dfa323709c06ec34cc96e73e0788e19934f:
KUnit: ffs: Validate all the __attribute_const__ annotations (2025-09-08 14:58:52 -0700)
----------------------------------------------------------------
ffs-const update for v6.18-rc1
- PCI: Fix theoretical underflow in use of ffs().
- Universally apply __attribute_const__ to all architecture's ffs()-family
of functions.
- Add KUnit tests for ffs() behavior and const-ness.
----------------------------------------------------------------
Kees Cook (18):
PCI: Test for bit underflow in pcie_set_readrq()
KUnit: Introduce ffs()-family tests
bitops: Add __attribute_const__ to generic ffs()-family implementations
csky: Add __attribute_const__ to ffs()-family implementations
x86: Add __attribute_const__ to ffs()-family implementations
powerpc: Add __attribute_const__ to ffs()-family implementations
sh: Add __attribute_const__ to ffs()-family implementations
alpha: Add __attribute_const__ to ffs()-family implementations
hexagon: Add __attribute_const__ to ffs()-family implementations
riscv: Add __attribute_const__ to ffs()-family implementations
openrisc: Add __attribute_const__ to ffs()-family implementations
m68k: Add __attribute_const__ to ffs()-family implementations
mips: Add __attribute_const__ to ffs()-family implementations
parisc: Add __attribute_const__ to ffs()-family implementations
s390: Add __attribute_const__ to ffs()-family implementations
xtensa: Add __attribute_const__ to ffs()-family implementations
sparc: Add __attribute_const__ to ffs()-family implementations
KUnit: ffs: Validate all the __attribute_const__ annotations
lib/Kconfig.debug | 14 +
lib/tests/Makefile | 1 +
arch/alpha/include/asm/bitops.h | 14 +-
arch/csky/include/asm/bitops.h | 8 +-
arch/hexagon/include/asm/bitops.h | 10 +-
arch/m68k/include/asm/bitops.h | 14 +-
arch/mips/include/asm/bitops.h | 8 +-
arch/openrisc/include/asm/bitops/__ffs.h | 2 +-
arch/openrisc/include/asm/bitops/__fls.h | 2 +-
arch/openrisc/include/asm/bitops/ffs.h | 2 +-
arch/openrisc/include/asm/bitops/fls.h | 2 +-
arch/parisc/include/asm/bitops.h | 6 +-
arch/powerpc/include/asm/bitops.h | 4 +-
arch/riscv/include/asm/bitops.h | 6 +-
arch/s390/include/asm/bitops.h | 10 +-
arch/sh/include/asm/bitops.h | 4 +-
arch/sparc/include/asm/bitops_64.h | 8 +-
arch/x86/include/asm/bitops.h | 12 +-
arch/xtensa/include/asm/bitops.h | 10 +-
include/asm-generic/bitops/__ffs.h | 2 +-
include/asm-generic/bitops/__fls.h | 2 +-
include/asm-generic/bitops/builtin-__ffs.h | 2 +-
include/asm-generic/bitops/builtin-__fls.h | 2 +-
include/asm-generic/bitops/builtin-fls.h | 2 +-
include/asm-generic/bitops/ffs.h | 2 +-
include/asm-generic/bitops/fls.h | 2 +-
include/asm-generic/bitops/fls64.h | 4 +-
include/linux/bitops.h | 2 +-
drivers/pci/pci.c | 6 +-
lib/clz_ctz.c | 8 +-
lib/tests/ffs_kunit.c | 566 +++++++++++++++++++++++++++++
31 files changed, 661 insertions(+), 76 deletions(-)
create mode 100644 lib/tests/ffs_kunit.c
--
Kees Cook