diff options
author | Linus Torvalds <[email protected]> | 2017-12-29 17:34:43 -0800 |
---|---|---|
committer | Linus Torvalds <[email protected]> | 2017-12-30 09:38:03 -0800 |
commit | 3ce120b16cc548472f80cf8644f90eda958cf1b6 (patch) | |
tree | 5e6c193f0c5b2b0985fdaab3c36d4c5a5cc49842 | |
parent | 5aa90a84589282b87666f92b6c3c917c8080a9bf (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-- | Makefile | 3 |
1 files changed, 3 insertions, 0 deletions
@@ -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) |