lib/Kconfig.ubsan: Remove 'default UBSAN' from UBSAN_INTEGER_WRAP

CONFIG_UBSAN_INTEGER_WRAP is 'default UBSAN', which is problematic for a
couple of reasons.

The first is that this sanitizer is under active development on the
compiler side to come up with a solution that is maintainable on the
compiler side and usable on the kernel side. As a result of this, there
are many warnings when the sanitizer is enabled that have no clear path
to resolution yet but users may see them and report them in the meantime.

The second is that this option was renamed from
CONFIG_UBSAN_SIGNED_WRAP, meaning that if a configuration has
CONFIG_UBSAN=y but CONFIG_UBSAN_SIGNED_WRAP=n and it is upgraded via
olddefconfig (common in non-interactive scenarios such as CI),
CONFIG_UBSAN_INTEGER_WRAP will be silently enabled again.

Remove 'default UBSAN' from CONFIG_UBSAN_INTEGER_WRAP until it is ready
for regular usage and testing from a broader community than the folks
actively working on the feature.

Cc: [email protected]
Fixes: 557f8c5 ("ubsan: Reintroduce signed overflow sanitizer")
Signed-off-by: Nathan Chancellor <[email protected]>
Link: https://lore.kernel.org/r/20250414-drop-default-ubsan-integer-wrap-v1-1-392522551d6b@kernel.org
Signed-off-by: Kees Cook <[email protected]>

Author: nathanchance

lib/Kconfig.ubsan

@@ -118,7 +118,6 @@ config UBSAN_UNREACHABLE
 
 config UBSAN_INTEGER_WRAP
 	bool "Perform checking for integer arithmetic wrap-around"
-	default UBSAN
 	depends on !COMPILE_TEST
 	depends on $(cc-option,-fsanitize-undefined-ignore-overflow-pattern=all)
 	depends on $(cc-option,-fsanitize=signed-integer-overflow)