Commit 72212675 authored Jan 24, 2013 by Yinghai Lu Committed by H. Peter Anvin Jan 29, 2013

x86, 64bit, mm: Mark data/bss/brk to nx



HPA said, we should not have RW and +x set at the time.

for kernel layout:
[    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]

before the patch, we have
---[ 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

after patch,, we get
---[ High Kernel Mapping ]---
0xffffffff80000000-0xffffffff81000000          16M                           pmd
0xffffffff81000000-0xffffffff82200000          18M     ro         PSE GLB x  pmd
0xffffffff82200000-0xffffffff82c00000          10M     ro         PSE GLB NX pmd
0xffffffff82c00000-0xffffffff82e00000           2M     RW             GLB NX pte
0xffffffff82e00000-0xffffffff83000000           2M     RW         PSE GLB NX pmd
0xffffffff83000000-0xffffffff83200000           2M     RW             GLB NX pte
0xffffffff83200000-0xffffffff83e00000          12M     RW         PSE GLB NX pmd
0xffffffff83e00000-0xffffffffa0000000         450M                           pmd

so data, bss, brk get NX ...

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1359058816-7615-33-git-send-email-yinghai@kernel.org


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

parent 6c902b65

arch/x86/mm/init_64.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -810,6 +810,7 @@ void mark_rodata_ro(void)
		unsigned long text_end = PAGE_ALIGN((unsigned long) &__stop___ex_table);
		unsigned long rodata_end = PAGE_ALIGN((unsigned long) &__end_rodata);
		unsigned long data_start = (unsigned long) &_sdata;
		unsigned long all_end = PFN_ALIGN(&_end);

		printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
		(end - start) >> 10);
		@@ -818,10 +819,10 @@ void mark_rodata_ro(void)
		kernel_set_to_readonly = 1;

		/*
		* The rodata section (but not the kernel text!) should also be
		* not-executable.
		* The rodata/data/bss/brk section (but not the kernel text!)
		* should also be not-executable.
		*/
		set_memory_nx(rodata_start, (end - rodata_start) >> PAGE_SHIFT);
		set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT);

		rodata_test();

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