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authorLinus Torvalds <torvalds@linux-foundation.org>2017-12-29 17:34:43 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>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 <alexander@tsoy.me> Reported-and-tested-by: Toralf Förster <toralf.foerster@gmx.de> Cc: stable@kernel.org Cc: Dave Hansen <dave.hansen@intel.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-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)

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