Re: [PATCH v3 3/3] MIPS: set stack/data protection as non-executable

[David Daney <ddaney.cavm@gmail.com>]

On 12/02/2014 05:58 PM, Leonid Yegoshin wrote:
> This is a last step of 3 patches which shift FPU emulation out of
> stack into protected area. So, it disables a default executable stack.
>
> Additionally, it sets a default data area non-executable protection.
>
> Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>

NAK!

Some programs require an executable stack, this patch will break them.

You can only select a non-executable stack in response to PT_GNU_STACK 
program headers in the ELF file of the executable program.

David Daney


> ---
>   arch/mips/include/asm/page.h |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
> index 3be81803595d..d49ba81cb4ed 100644
> --- a/arch/mips/include/asm/page.h
> +++ b/arch/mips/include/asm/page.h
> @@ -230,7 +230,7 @@ extern int __virt_addr_valid(const volatile void *kaddr);
>   #define virt_addr_valid(kaddr)						\
>   	__virt_addr_valid((const volatile void *) (kaddr))
>
> -#define VM_DATA_DEFAULT_FLAGS	(VM_READ | VM_WRITE | VM_EXEC | \
> +#define VM_DATA_DEFAULT_FLAGS	(VM_READ | VM_WRITE | \
>   				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
>
>   #define UNCAC_ADDR(addr)	((addr) - PAGE_OFFSET + UNCAC_BASE)
>
>
>
>