The patch titled
Subject: ./Makefile: explain stack-protector-strong CONFIG logic
has been removed from the -mm tree. Its filename was
kbuild-explain-stack-protector-strong-config-logic.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
Subject: ./Makefile: explain stack-protector-strong CONFIG logic
This adds a hopefully helpful comment above the (seemingly weird) compiler
flag selection logic.
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Michal Marek <mmarek@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Makefile | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff -puN Makefile~kbuild-explain-stack-protector-strong-config-logic Makefile
--- a/Makefile~kbuild-explain-stack-protector-strong-config-logic
+++ a/Makefile
@@ -636,6 +636,22 @@ KBUILD_CFLAGS += $(call cc-option,-Wfram
endif
# Handle stack protector mode.
+#
+# Since kbuild can potentially perform two passes (first with the old
+# .config values and then with updated .config values), we cannot error out
+# if a desired compiler option is unsupported. If we were to error, kbuild
+# could never get to the second pass and actually notice that we changed
+# the option to something that was supported.
+#
+# Additionally, we don't want to fallback and/or silently change which compiler
+# flags will be used, since that leads to producing kernels with different
+# security feature characteristics depending on the compiler used. ("But I
+# selected CC_STACKPROTECTOR_STRONG! Why did it build with _REGULAR?!")
+#
+# The middle ground is to warn here so that the failed option is obvious, but
+# to let the build fail with bad compiler flags so that we can't produce a
+# kernel when there is a CONFIG and compiler mismatch.
+#
ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
stackp-flag := -fstack-protector
ifeq ($(call cc-option, $(stackp-flag)),)
_
Patches currently in -mm which might be from keescook@xxxxxxxxxxxx are
origin.patch
lib-vsprintf-add-%pt-format-specifier.patch
binfmt_elfc-use-get_random_int-to-fix-entropy-depleting.patch
linux-next.patch
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