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

commit 72212675d1c96f5db8ec6fb35701879911193158 upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 44b93da..a2340ee 100644 (file)
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -778,6 +778,7 @@ 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);
@@ -786,10 +787,10 @@ 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();