Makefile: Enable -Wcast-function-type
In order to make sure new function cast mismatches are not introduced
in the kernel (to avoid tripping CFI checking), the kernel should be
globally built with -Wcast-function-type.
Link: https://github.com/KSPP/linux/issues/20
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
diff --git a/Makefile b/Makefile
index 9e12c14..5a8cde6 100644
--- a/Makefile
+++ b/Makefile
@@ -953,6 +953,11 @@
# disable pointer signed / unsigned warnings in gcc 4.0
KBUILD_CFLAGS += -Wno-pointer-sign
+# In order to make sure new function cast mismatches are not introduced
+# in the kernel (to avoid tripping CFI checking), the kernel should be
+# globally built with -Wcast-function-type.
+KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
+
# disable stringop warnings in gcc 8+
KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)