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SubjectRe: [PATCH v2 5/5] x86/head/64: Disable stack protection for head$(BITS).o
On Thu, Oct 08, 2020 at 03:16:23PM -0400, Arvind Sankar wrote:
> On 64-bit, the startup_64_setup_env() function added in
> 866b556efa12 ("x86/head/64: Install startup GDT")
> has stack protection enabled because of set_bringup_idt_handler().
>
> At this point, %gs is not yet initialized, and this doesn't cause a
> crash only because the #PF handler from the decompressor stub is still
> installed and handles the page fault.
>
> Disable stack protection for the whole file, and do it on 32-bit as
> well to avoid surprises.
>
> Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
> ---
> arch/x86/kernel/Makefile | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 04ceea8f4a89..68608bd892c0 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -47,6 +47,8 @@ endif
> # non-deterministic coverage.
> KCOV_INSTRUMENT := n
>
> +CFLAGS_head$(BITS).o += -fno-stack-protector
> +
> CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace
>
> obj-y := process_$(BITS).o signal.o
> --
> 2.26.2

Reviewed-by: Joerg Roedel <jroedel@suse.de>

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