From 3ce120b16cc548472f80cf8644f90eda958cf1b6 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Fri, 29 Dec 2017 17:34:43 -0800 Subject: 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 Reported-and-tested-by: Toralf Förster Cc: stable@kernel.org Cc: Dave Hansen Cc: Jiri Kosina Cc: Andy Lutomirski Signed-off-by: Linus Torvalds --- Makefile | 3 +++ 1 file changed, 3 insertions(+) (limited to 'Makefile') 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) -- cgit v1.2.3-55-g7522