Re: [RFC] stack and heap are executable on x86_64

From: Yinghai Lu
Date: Fri Dec 21 2012 - 16:26:31 EST

On Fri, Dec 21, 2012 at 9:36 AM, H. Peter Anvin <hpa@xxxxxxxxx> 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

---[ 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

[ 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.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at