diff mbox

[1/8] x86, kaslr: get kaslr_enabled back correctly

Message ID CAE9FiQV6EnF-3eb97-wtdfyfr5T=HZtpxHnmTYK4OGMyYwKq0w@mail.gmail.com (mailing list archive)
State New, archived
Delegated to: Bjorn Helgaas
Headers show

Commit Message

Yinghai Lu March 2, 2015, 10:10 p.m. UTC 
On Mon, Mar 2, 2015 at 12:25 PM, Borislav Petkov <bp@suse.de> wrote:

>  unsigned char *choose_kernel_location(struct boot_params *params,
> diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
> index 34d047c98284..26d62f4b27b9 100644
> --- a/arch/x86/boot/compressed/vmlinux.lds.S
> +++ b/arch/x86/boot/compressed/vmlinux.lds.S
> @@ -29,6 +29,10 @@ SECTIONS
>         .rodata..compressed : {
>                 *(.rodata..compressed)
>         }
> +       .setup_data : {
> +               _setup_data = . ;
> +               *(.setup_data)
> +       }
>         .text : {
>                 _text = .;      /* Text */
>                 *(.text)

That does not help, we will still have overlap between copied Zo
vmlinux and decompressed Vo vmlinux

because the Zo vmlinux is copied to middle of buffer instead of end of
the buffer.

definition:
Zo vmliunx: arch/x86/boot/compressed/vmlinux, from
arch/x86/boot/compressed/vmlinux.lds.S
Vo vmlinux: vmlinux from arch/x86/kernel/vmlinux.lds.S

BTW, found more problem about run_size for kaslr, we should use
init_size instead.

Here the three patches that should go into v4.0. Help Ingo will be
happy with updated change log.

Thanks

Yinghai
diff mbox

Patch

Subject: [PATCH v2] x86, kaslr: get kaslr_enabled back correctly

commit f47233c2d34f ("x86/mm/ASLR: Propagate base load address calculation")
is using address as vaule for kaslr_enabled.

That will random kaslr_enabled get that set or cleared.
Will have problem for system really have kaslr enabled.

-v2: update changelog.

Fixes: f47233c2d34f ("x86/mm/ASLR: Propagate base load address calculation")
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/kernel/setup.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Index: linux-2.6/arch/x86/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup.c
+++ linux-2.6/arch/x86/kernel/setup.c
@@ -429,7 +429,13 @@  static void __init reserve_initrd(void)
 
 static void __init parse_kaslr_setup(u64 pa_data, u32 data_len)
 {
-	kaslr_enabled = (bool)(pa_data + sizeof(struct setup_data));
+	/* kaslr_setup_data is defined in aslr.c */
+	unsigned char *data;
+	unsigned long offset = sizeof(struct setup_data);
+
+	data = early_memremap(pa_data, offset + 1);
+	kaslr_enabled = *(data + offset);
+	early_memunmap(data, offset + 1);
 }
 
 static void __init parse_setup_data(void)