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Patch "x86/mm: Set NX on gap between __ex_table and rodata" has been added to the 4.1-stable tree

PATCH [email protected] 1 participant 1 message Oct 13, 2015

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This is a note to let you know that I've just added the patch titled

x86/mm: Set NX on gap between __ex_table and rodata

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     x86-mm-set-nx-on-gap-between-__ex_table-and-rodata.patch

and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From ab76f7b4ab2397ffdd2f1eb07c55697d19991d10 Mon Sep 17 00:00:00 2001

From: Stephen Smalley <[email protected]>
Date: Thu, 1 Oct 2015 09:04:22 -0400
Subject: x86/mm: Set NX on gap between __ex_table and rodata

From: Stephen Smalley <[email protected]>

commit ab76f7b4ab2397ffdd2f1eb07c55697d19991d10 upstream.

Unused space between the end of __ex_table and the start of rodata can be left W+x in the kernel page tables. Extend the setting of the NX bit to cover this gap by starting from text_end rather than rodata_start.

Before:
---[ High Kernel Mapping ]---

  0xffffffff80000000-0xffffffff81000000          16M                               pmd
  0xffffffff81000000-0xffffffff81600000           6M     ro         PSE     GLB x  pmd
  0xffffffff81600000-0xffffffff81754000        1360K     ro                 GLB x  pte
  0xffffffff81754000-0xffffffff81800000         688K     RW                 GLB x  pte
  0xffffffff81800000-0xffffffff81a00000           2M     ro         PSE     GLB NX pmd
  0xffffffff81a00000-0xffffffff81b3b000        1260K     ro                 GLB NX pte
  0xffffffff81b3b000-0xffffffff82000000        4884K     RW                 GLB NX pte
  0xffffffff82000000-0xffffffff82200000           2M     RW         PSE     GLB NX pmd

0xffffffff82200000-0xffffffffa0000000 478M pmd

After:
---[ High Kernel Mapping ]---

  0xffffffff80000000-0xffffffff81000000          16M                               pmd
  0xffffffff81000000-0xffffffff81600000           6M     ro         PSE     GLB x  pmd
  0xffffffff81600000-0xffffffff81754000        1360K     ro                 GLB x  pte
  0xffffffff81754000-0xffffffff81800000         688K     RW                 GLB NX pte
  0xffffffff81800000-0xffffffff81a00000           2M     ro         PSE     GLB NX pmd
  0xffffffff81a00000-0xffffffff81b3b000        1260K     ro                 GLB NX pte
  0xffffffff81b3b000-0xffffffff82000000        4884K     RW                 GLB NX pte
  0xffffffff82000000-0xffffffff82200000           2M     RW         PSE     GLB NX pmd

0xffffffff82200000-0xffffffffa0000000 478M pmd

Signed-off-by Stephen Smalley <[email protected]>
Acked-by Kees Cook <[email protected]>
Cc Linus Torvalds <[email protected]>
Cc Mike Galbraith <[email protected]>
Cc Peter Zijlstra <[email protected]>
Cc Thomas Gleixner <[email protected]>
Cc [email protected]
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Ingo Molnar <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 arch/x86/mm/init_64.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/mm/init_64.c +1 -1
@@ -1132,7 +1132,7 @@ void mark_rodata_ro(void)
 	 * has been zapped already via cleanup_highmem().
 	 */
 	all_end = roundup((unsigned long)_brk_end, PMD_SIZE);
-	set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT);
+	set_memory_nx(text_end, (all_end - text_end) >> PAGE_SHIFT);
 
 	rodata_test();

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/x86-mm-set-nx-on-gap-between-__ex_table-and-rodata.patch