https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102317
--- Comment #9 from Kees Cook <kees at outflux dot net> ---
(In reply to Jakub Jelinek from comment #8)
> So, instead (when building the kernel with sanitization) build with
> -fsanitize=signed-integer-overflow and no -fno-strict-overflow, and
> the routines where you want wrapv behavior and not runtime traps build with
> optimize ("wrapv", "wrapv-pointer") attribute?
__attribute__((optimize)) is documented as not for production use ("for
debugging purposes only"):
https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-optimize-function-attribute
and the kernel has hit multiple problems with it. As such, all use has been
removed, for example:
https://lore.kernel.org/lkml/20201027205723.12514-1-a...@kernel.org/
https://lore.kernel.org/lkml/20201028080433.26799-1-a...@kernel.org/
https://lore.kernel.org/lkml/20210118105557.186614-3-adrian.ra...@collabora.com/
If there were an __attribute__((wrapv)) and __attribute__((wrapv-pointer)), we
could create the wrapping helpers with those and
__attribute__((no_sanitize("signed-integer-overflow")))
FWIW, I've been trying to track this issue in the kernel here:
https://github.com/KSPP/linux/issues/26
