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authorLinus Torvalds <[email protected]>2017-12-29 17:34:43 -0800
committerLinus Torvalds <[email protected]>2017-12-30 09:38:03 -0800
commit3ce120b16cc548472f80cf8644f90eda958cf1b6 (patch)
tree5e6c193f0c5b2b0985fdaab3c36d4c5a5cc49842
parent5aa90a84589282b87666f92b6c3c917c8080a9bf (diff)
kbuild: add '-fno-stack-check' to kernel build options
It appears that hardened gentoo enables "-fstack-check" by default for gcc. That doesn't work _at_all_ for the kernel, because the kernel stack doesn't act like a user stack at all: it's much smaller, and it doesn't auto-expand on use. So the extra "probe one page below the stack" code generated by -fstack-check just breaks the kernel in horrible ways, causing infinite double faults etc. [ I have to say, that the particular code gcc generates looks very stupid even for user space where it works, but that's a separate issue. ] Reported-and-tested-by: Alexander Tsoy <[email protected]> Reported-and-tested-by: Toralf Förster <[email protected]> Cc: [email protected] Cc: Dave Hansen <[email protected]> Cc: Jiri Kosina <[email protected]> Cc: Andy Lutomirski <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
-rw-r--r--Makefile3
1 files changed, 3 insertions, 0 deletions
diff --git a/Makefile b/Makefile
index ac8c441866b7..92b74bcd3c2a 100644
--- a/Makefile
+++ b/Makefile
@@ -789,6 +789,9 @@ KBUILD_CFLAGS += $(call cc-disable-warning, pointer-sign)
# disable invalid "can't wrap" optimizations for signed / pointers
KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow)
+# Make sure -fstack-check isn't enabled (like gentoo apparently did)
+KBUILD_CFLAGS += $(call cc-option,-fno-stack-check,)
+
# conserve stack if available
KBUILD_CFLAGS += $(call cc-option,-fconserve-stack)