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authorLinus Torvalds <torvalds@linux-foundation.org>2017-12-29 17:34:43 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-01-02 20:35:10 +0100
commitb929ccccbc8c22736d1fd722da181e275465f5a6 (patch)
tree43eca75417e1050aa4605d685fd5c23525d3cd60 /Makefile
parent04bdf71d9f7412364e9bae93f321e6bf776cd1d4 (diff)
kbuild: add '-fno-stack-check' to kernel build options
commit 3ce120b16cc548472f80cf8644f90eda958cf1b6 upstream. 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: 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Makefile')
-rw-r--r--Makefile3
1 files changed, 3 insertions, 0 deletions
diff --git a/Makefile b/Makefile
index 64eb0bf614ee..dc9012a6d14b 100644
--- a/Makefile
+++ b/Makefile
@@ -788,6 +788,9 @@ 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)