* [PATCH] x86/mm: Set NX on gap between __ex_table and rodata
@ 2015-10-01 13:04 Stephen Smalley
2015-10-01 16:35 ` Kees Cook
2015-10-02 7:45 ` [tip:x86/urgent] " tip-bot for Stephen Smalley
0 siblings, 2 replies; 3+ messages in thread
From: Stephen Smalley @ 2015-10-01 13:04 UTC (permalink / raw)
To: x86; +Cc: linux-kernel, keescook, Stephen Smalley
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 <sds@tycho.nsa.gov>
---
arch/x86/mm/init_64.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 30564e2..df48430 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -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();
--
2.1.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] x86/mm: Set NX on gap between __ex_table and rodata
2015-10-01 13:04 [PATCH] x86/mm: Set NX on gap between __ex_table and rodata Stephen Smalley
@ 2015-10-01 16:35 ` Kees Cook
2015-10-02 7:45 ` [tip:x86/urgent] " tip-bot for Stephen Smalley
1 sibling, 0 replies; 3+ messages in thread
From: Kees Cook @ 2015-10-01 16:35 UTC (permalink / raw)
To: Stephen Smalley; +Cc: x86, LKML
On Thu, Oct 1, 2015 at 6:04 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
> 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 <sds@tycho.nsa.gov>
Acked-by: Kees Cook <keescook@chromium.org>
-Kees
> ---
> arch/x86/mm/init_64.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 30564e2..df48430 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -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();
>
> --
> 2.1.0
>
--
Kees Cook
Chrome OS Security
^ permalink raw reply [flat|nested] 3+ messages in thread
* [tip:x86/urgent] x86/mm: Set NX on gap between __ex_table and rodata
2015-10-01 13:04 [PATCH] x86/mm: Set NX on gap between __ex_table and rodata Stephen Smalley
2015-10-01 16:35 ` Kees Cook
@ 2015-10-02 7:45 ` tip-bot for Stephen Smalley
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot for Stephen Smalley @ 2015-10-02 7:45 UTC (permalink / raw)
To: linux-tip-commits
Cc: mingo, tglx, linux-kernel, torvalds, hpa, peterz, efault, stable,
keescook, sds
Commit-ID: ab76f7b4ab2397ffdd2f1eb07c55697d19991d10
Gitweb: http://git.kernel.org/tip/ab76f7b4ab2397ffdd2f1eb07c55697d19991d10
Author: Stephen Smalley <sds@tycho.nsa.gov>
AuthorDate: Thu, 1 Oct 2015 09:04:22 -0400
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 2 Oct 2015 09:21:06 +0200
x86/mm: Set NX on gap between __ex_table and rodata
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 <sds@tycho.nsa.gov>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: <stable@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1443704662-3138-1-git-send-email-sds@tycho.nsa.gov
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/mm/init_64.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 30564e2..df48430 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -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();
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2015-10-01 13:04 [PATCH] x86/mm: Set NX on gap between __ex_table and rodata Stephen Smalley
2015-10-01 16:35 ` Kees Cook
2015-10-02 7:45 ` [tip:x86/urgent] " tip-bot for Stephen Smalley
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