Commit 1332429b authored by Kees Cook's avatar Kees Cook Committed by Linus Torvalds

./Makefile: explain stack-protector-strong CONFIG logic

This adds a hopefully helpful comment above the (seemingly weird) compiler
flag selection logic.
Signed-off-by: default avatarKees Cook <>
Suggested-by: default avatarAndrew Morton <>
Cc: Andi Kleen <>
Cc: Randy Dunlap <>
Cc: Michal Marek <>
Cc: Michal Hocko <>
Cc: Stephen Rothwell <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 5838d444
......@@ -636,6 +636,22 @@ KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
# Handle stack protector mode.
# Since kbuild can potentially perform two passes (first with the old
# .config values and then with updated .config values), we cannot error out
# if a desired compiler option is unsupported. If we were to error, kbuild
# could never get to the second pass and actually notice that we changed
# the option to something that was supported.
# Additionally, we don't want to fallback and/or silently change which compiler
# flags will be used, since that leads to producing kernels with different
# security feature characteristics depending on the compiler used. ("But I
# selected CC_STACKPROTECTOR_STRONG! Why did it build with _REGULAR?!")
# The middle ground is to warn here so that the failed option is obvious, but
# to let the build fail with bad compiler flags so that we can't produce a
# kernel when there is a CONFIG and compiler mismatch.
stackp-flag := -fstack-protector
ifeq ($(call cc-option, $(stackp-flag)),)
Markdown is supported
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment