From: Linus Torvalds Date: Sat, 30 Dec 2017 01:34:43 +0000 (-0800) Subject: kbuild: add '-fno-stack-check' to kernel build options X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=6b85c8c37160135bd9b3fb1dc652ddd230093c25 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 Reported-and-tested-by: Toralf Förster Cc: Dave Hansen Cc: Jiri Kosina Cc: Andy Lutomirski Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- diff --git a/Makefile b/Makefile index 71876659ace6..6aaceec17ea2 100644 --- a/Makefile +++ b/Makefile @@ -631,6 +631,9 @@ 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)