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

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Message-ID: <5481EB52.6060706@gmail.com>
Date:	Fri, 05 Dec 2014 09:28:50 -0800
From:	David Daney <ddaney.cavm@...il.com>
To:	Leonid Yegoshin <Leonid.Yegoshin@...tec.com>
CC:	linux-mips@...ux-mips.org, Zubair.Kakakhel@...tec.com,
	geert+renesas@...der.be, david.daney@...ium.com,
	peterz@...radead.org, paul.gortmaker@...driver.com,
	davidlohr@...com, macro@...ux-mips.org, chenhc@...ote.com,
	cl@...ux.com, mingo@...nel.org, richard@....at, zajec5@...il.com,
	james.hogan@...tec.com, keescook@...omium.org, tj@...nel.org,
	alex@...x-smith.me.uk, pbonzini@...hat.com, blogic@...nwrt.org,
	paul.burton@...tec.com, qais.yousef@...tec.com,
	linux-kernel@...r.kernel.org, ralf@...ux-mips.org,
	markos.chandras@...tec.com, dengcheng.zhu@...tec.com,
	manuel.lauss@...il.com, lars.persson@...s.com
Subject: Re: [PATCH v3 3/3] MIPS: set stack/data protection as non-executable

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@...tec.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)
>
>
>
>

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