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kbuild: add '-fno-stack-check' to kernel build options
commit 3ce120b16c
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>
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1 changed files with 3 additions and 0 deletions
3
Makefile
3
Makefile
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@ -802,6 +802,9 @@ KBUILD_CFLAGS += $(call cc-disable-warning, pointer-sign)
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# disable invalid "can't wrap" optimizations for signed / pointers
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# disable invalid "can't wrap" optimizations for signed / pointers
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KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow)
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KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow)
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# Make sure -fstack-check isn't enabled (like gentoo apparently did)
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KBUILD_CFLAGS += $(call cc-option,-fno-stack-check,)
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# conserve stack if available
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# conserve stack if available
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KBUILD_CFLAGS += $(call cc-option,-fconserve-stack)
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KBUILD_CFLAGS += $(call cc-option,-fconserve-stack)
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