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SubjectRe: [RFC] stack and heap are executable on x86_64
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On Fri, Dec 21, 2012 at 1:26 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Fri, Dec 21, 2012 at 9:36 AM, H. Peter Anvin <hpa@zytor.com> wrote:
>> We should NEVER have RW + x at the same time (at least when the kernel
>> is compiled properly.) Looks like your patch does get rid of a bunch of
>> stuff in the low mapping -- although the low mapping really should never
>> be +x at all -- but there are still problems with the high mapping
>
> after enabling CONFIG_DEBUG_RODATA
>
> get
> ---[ High Kernel Mapping ]---
> 0xffffffff80000000-0xffffffff81000000 16M pmd
> 0xffffffff81000000-0xffffffff82200000 18M ro PSE GLB x pmd
> 0xffffffff82200000-0xffffffff82c00000 10M ro PSE GLB NX pmd
> 0xffffffff82c00000-0xffffffff82dc9000 1828K RW GLB x pte
> 0xffffffff82dc9000-0xffffffff82e00000 220K RW GLB NX pte
> 0xffffffff82e00000-0xffffffff83000000 2M RW PSE GLB NX pmd
> 0xffffffff83000000-0xffffffff8313a000 1256K RW GLB NX pte
> 0xffffffff8313a000-0xffffffff83200000 792K RW GLB x pte
> 0xffffffff83200000-0xffffffff83e00000 12M RW PSE GLB x pmd
> 0xffffffff83e00000-0xffffffffa0000000 450M pmd
>
> for
> [ 0.000000] Kernel Layout:
> [ 0.000000] .text: [0x01000000-0x021434f8]
> [ 0.000000] .rodata: [0x02200000-0x02a13fff]
> [ 0.000000] .data: [0x02c00000-0x02dc763f]
> [ 0.000000] .init: [0x02dc9000-0x0312cfff]
> [ 0.000000] .bss: [0x0313b000-0x03dd6fff]
> [ 0.000000] .brk: [0x03dd7000-0x03dfffff]
>
> looks like .data, .bss, .brk should not have x set.

please check attached patch that set NX for data/bss/brk with 64bit.

Thanks

Yinghai
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