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This silently breaks third-party modules whose source code (e.g. VMware vmnet/vmmon) triggers UBSAN UB checks at runtime, causing packet-forwarding failures and VM instability while the module itself loads successfully. Make UBSAN opt-in for external modules: skip the is-kernel-object 'y' fallback when KBUILD_EXTMOD is set. External modules that explicitly need UBSAN can still opt in by setting UBSAN_SANITIZE := y. In-kernel module builds are not affected. Signed-off-by: Ferran Duarri --- scripts/Makefile.lib | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 0718e39cedda..393af3f970af 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -74,10 +74,10 @@ endif ifeq ($(CONFIG_UBSAN),y) _c_flags += $(if $(patsubst n%,, \ - $(UBSAN_SANITIZE_$(target-stem).o)$(UBSAN_SANITIZE)$(is-kernel-object)), \ + $(UBSAN_SANITIZE_$(target-stem).o)$(UBSAN_SANITIZE)$(if $(KBUILD_EXTMOD),,$(is-kernel-object))), \ $(CFLAGS_UBSAN)) _c_flags += $(if $(patsubst n%,, \ - $(UBSAN_INTEGER_WRAP_$(target-stem).o)$(UBSAN_SANITIZE_$(target-stem).o)$(UBSAN_INTEGER_WRAP)$(UBSAN_SANITIZE)$(is-kernel-object)), \ + $(UBSAN_INTEGER_WRAP_$(target-stem).o)$(UBSAN_SANITIZE_$(target-stem).o)$(UBSAN_INTEGER_WRAP)$(UBSAN_SANITIZE)$(if $(KBUILD_EXTMOD),,$(is-kernel-object))), \ $(CFLAGS_UBSAN_INTEGER_WRAP)) endif