[PATCH 0/5] overflow: Introduce wrapping helpers

Kees Cook
2024-01-29T18:34:14Z

Hi,

In preparation for gaining instrumentation for signed[1], unsigned[2], and
pointer[3] wrap-around, expand the overflow header to include wrap-around
helpers that can be used to annotate arithmetic where wrapped calculations
are expected (e.g. atomics).

After spending time getting the unsigned integer wrap-around sanitizer
running warning-free on a basic x86_64 boot[4], I think the *_wrap()
helpers first argument being the output type makes the most sense (as
suggested by Rasmus).

-Kees

Link: https://github.com/KSPP/linux/issues/26 [1]
Link: https://github.com/KSPP/linux/issues/27 [2]
Link: https://github.com/KSPP/linux/issues/344 [3]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/log/?h=devel/overflow/enable-unsigned-sanitizer [4]

Kees Cook (5):
overflow: Adjust check_*_overflow() kern-doc to reflect results
overflow: Expand check_add_overflow() for pointer addition
overflow: Introduce add_would_overflow()
overflow: Introduce add_wrap(), sub_wrap(), and mul_wrap()
overflow: Introduce inc_wrap() and dec_wrap()

include/linux/compiler_types.h | 10 ++
include/linux/overflow.h | 164 ++++++++++++++++++++++++++++++---
lib/overflow_kunit.c | 77 ++++++++++++++--
3 files changed, 228 insertions(+), 23 deletions(-)

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2.34.1