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    Subject[PATCH 32/35] x86, 64bit, mm: Mark data/bss/brk to nx
    Date
    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>
    ---
    arch/x86/mm/init_64.c | 7 ++++---
    1 file changed, 4 insertions(+), 3 deletions(-)

    diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
    index 64e6fe0..edaa2da 100644
    --- a/arch/x86/mm/init_64.c
    +++ b/arch/x86/mm/init_64.c
    @@ -808,6 +808,7 @@ void mark_rodata_ro(void)
    unsigned long end = (unsigned long) &__end_rodata_hpage_align;
    unsigned long text_end = PFN_ALIGN(&__stop___ex_table);
    unsigned long rodata_end = PFN_ALIGN(&__end_rodata);
    + unsigned long all_end = PFN_ALIGN(&_end);

    printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
    (end - start) >> 10);
    @@ -816,10 +817,10 @@ 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();

    --
    1.7.10.4


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