[PATCH 0/1] grub security update (CVE-2015-8370)

[PATCH 0/1] grub security update (CVE-2015-8370)

[Leo Famulari]

This patch for Grub2 fixes CVE-2015-8370 [0][1]. The source of the patch
is [0].

One thing to note is that there doesn't seem to be any response from
upstream, yet. However, at least some distros are applying the patch
[2][3].

AFAIK, GuixSD doesn't support authenticated Grub yet, so this
vulnerability doesn't manifest itself. Because of this, I did not test
if the patch fixes the bug. I did test that Grub works as expected with
the patch applied.

If I'm wrong, and it's possible to set up authenticated Grub on GuixSD,
I can test that, too.

I tested this patch on bare-metal i686, like this:

0) Installed GuixSD on i686 laptop.
1) Cloned Guix source tree and built Guix.
2) Applied this patch, and built Grub as a sanity check.
`./pre-inst-env guix build grub`
3) Reconfigured the system against the source tree.
`./pre-inst-env guix system reconfigure config.scm`
4) Successfully rebooted several times into different generations of the 
system.

[0]
http://hmarco.org/bugs/CVE-2015-8370-Grub2-authentication-bypass.html

[1]
https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-8370

[2] Select "Fedora 23" from the "RELEASE" menu:
https://apps.fedoraproject.org/packages/grub2/sources/spec/

[3] See "changelog":
https://packages.qa.debian.org/g/grub2.html

Leo Famulari (1):
  gnu: grub: Add fix for CVE-2015-8730.

 gnu/packages/grub.scm                         |  4 ++-
 gnu/packages/patches/grub-CVE-2015-8370.patch | 45 +++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/grub-CVE-2015-8370.patch

-- 
2.6.2

[PATCH 1/1] gnu: grub: Add fix for CVE-2015-8730.

[Leo Famulari]

* gnu/packages/patches/grub-CVE-2015-8370.patch: New file.
* gnu/packages/grub.scm: Apply patch.
---
 gnu/packages/grub.scm                         |  4 ++-
 gnu/packages/patches/grub-CVE-2015-8370.patch | 45 +++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/grub-CVE-2015-8370.patch

diff --git a/gnu/packages/grub.scm b/gnu/packages/grub.scm
index 79fc2f0..96d284c 100644
--- a/gnu/packages/grub.scm
+++ b/gnu/packages/grub.scm
@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
+;;; Copyright © 2015 Leo Famulari <leo@famulari.name>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -83,7 +84,8 @@
               (base32
                "0n64hpmsccvicagvr0c6v0kgp2yw0kgnd3jvsyd26cnwgs7c6kkq"))
              (patches (list (search-patch "grub-gets-undeclared.patch")
-                            (search-patch "grub-freetype.patch")))))
+                            (search-patch "grub-freetype.patch")
+                            (search-patch "grub-CVE-2015-8370.patch")))))
     (build-system gnu-build-system)
     (arguments
      '(#:configure-flags '("--disable-werror")
diff --git a/gnu/packages/patches/grub-CVE-2015-8370.patch b/gnu/packages/patches/grub-CVE-2015-8370.patch
new file mode 100644
index 0000000..5701b54
--- /dev/null
+++ b/gnu/packages/patches/grub-CVE-2015-8370.patch
@@ -0,0 +1,45 @@
+From 88c9657960a6c5d3673a25c266781e876c181add Mon Sep 17 00:00:00 2001
+From: Hector Marco-Gisbert <hecmargi@upv.es>
+Date: Fri, 13 Nov 2015 16:21:09 +0100
+Subject: [PATCH] Fix security issue when reading username and password
+
+  This patch fixes two integer underflows at:
+    * grub-core/lib/crypto.c
+    * grub-core/normal/auth.c
+
+Signed-off-by: Hector Marco-Gisbert <hecmargi@upv.es>
+Signed-off-by: Ismael Ripoll-Ripoll <iripoll@disca.upv.es>
+---
+ grub-core/lib/crypto.c  | 2 +-
+ grub-core/normal/auth.c | 2 +-
+ 2 files changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/grub-core/lib/crypto.c b/grub-core/lib/crypto.c
+index 010e550..524a3d8 100644
+--- a/grub-core/lib/crypto.c
++++ b/grub-core/lib/crypto.c
+@@ -468,7 +468,7 @@ grub_password_get (char buf[], unsigned buf_size)
+ 	  break;
+ 	}
+ 
+-      if (key == '\b')
++      if (key == '\b' && cur_len)
+ 	{
+ 	  cur_len--;
+ 	  continue;
+diff --git a/grub-core/normal/auth.c b/grub-core/normal/auth.c
+index c6bd96e..5782ec5 100644
+--- a/grub-core/normal/auth.c
++++ b/grub-core/normal/auth.c
+@@ -172,7 +172,7 @@ grub_username_get (char buf[], unsigned buf_size)
+ 	  break;
+ 	}
+ 
+-      if (key == '\b')
++      if (key == '\b' && cur_len)
+ 	{
+ 	  cur_len--;
+ 	  grub_printf ("\b");
+-- 
+1.9.1
+
-- 
2.6.2

Re: [PATCH 0/1] grub security update (CVE-2015-8370)

[Ludovic Courtès]

Leo Famulari <leo@famulari.name> skribis:

> This patch for Grub2 fixes CVE-2015-8370 [0][1]. The source of the patch
> is [0].
>
> One thing to note is that there doesn't seem to be any response from
> upstream, yet. However, at least some distros are applying the patch
> [2][3].
>
> AFAIK, GuixSD doesn't support authenticated Grub yet, so this
> vulnerability doesn't manifest itself.

Right, but still worth fixing.

And perhaps someone will get the idea of adding authentication in our
GRUB support code?  :-)

> I tested this patch on bare-metal i686, like this:

Thanks for testing and explaining how you tested it.

Leo Famulari <leo@famulari.name> skribis:

> * gnu/packages/patches/grub-CVE-2015-8370.patch: New file.
> * gnu/packages/grub.scm: Apply patch.
> ---
>  gnu/packages/grub.scm                         |  4 ++-
>  gnu/packages/patches/grub-CVE-2015-8370.patch | 45 +++++++++++++++++++++++++++
>  2 files changed, 48 insertions(+), 1 deletion(-)

Please make sure to add the patch to gnu-system.am.

OK to push with this change.

Thank you!

Ludo’.

Re: [PATCH 0/1] grub security update (CVE-2015-8370)

[Leo Famulari]

On Sun, Dec 20, 2015 at 11:19:44PM +0100, Ludovic Courtès wrote:
> Leo Famulari <leo@famulari.name> skribis:
> 
> > * gnu/packages/patches/grub-CVE-2015-8370.patch: New file.
> > * gnu/packages/grub.scm: Apply patch.
> > ---
> >  gnu/packages/grub.scm                         |  4 ++-
> >  gnu/packages/patches/grub-CVE-2015-8370.patch | 45 +++++++++++++++++++++++++++
> >  2 files changed, 48 insertions(+), 1 deletion(-)
> 
> Please make sure to add the patch to gnu-system.am.

Done.

> OK to push with this change.

To master or security-updates? 

`guix refresh -l grub` reports no dependents other than itself.

Re: [PATCH 0/1] grub security update (CVE-2015-8370)

[Ludovic Courtès]

Leo Famulari <leo@famulari.name> skribis:

> On Sun, Dec 20, 2015 at 11:19:44PM +0100, Ludovic Courtès wrote:
>> Leo Famulari <leo@famulari.name> skribis:
>> 
>> > * gnu/packages/patches/grub-CVE-2015-8370.patch: New file.
>> > * gnu/packages/grub.scm: Apply patch.
>> > ---
>> >  gnu/packages/grub.scm                         |  4 ++-
>> >  gnu/packages/patches/grub-CVE-2015-8370.patch | 45 +++++++++++++++++++++++++++
>> >  2 files changed, 48 insertions(+), 1 deletion(-)
>> 
>> Please make sure to add the patch to gnu-system.am.
>
> Done.
>
>> OK to push with this change.
>
> To master or security-updates? 
>
> `guix refresh -l grub` reports no dependents other than itself.

Right, so pushing to ‘master’ is fine.

Thanks,
Ludo’.

Re: [PATCH 0/1] grub security update (CVE-2015-8370)

[Leo Famulari]

On Mon, Dec 21, 2015 at 11:39:53AM +0100, Ludovic Courtès wrote:
> Leo Famulari <leo@famulari.name> skribis:
> 
> > On Sun, Dec 20, 2015 at 11:19:44PM +0100, Ludovic Courtès wrote:
> >> Leo Famulari <leo@famulari.name> skribis:
> >> 
> >> > * gnu/packages/patches/grub-CVE-2015-8370.patch: New file.
> >> > * gnu/packages/grub.scm: Apply patch.
> >> > ---
> >> >  gnu/packages/grub.scm                         |  4 ++-
> >> >  gnu/packages/patches/grub-CVE-2015-8370.patch | 45 +++++++++++++++++++++++++++
> >> >  2 files changed, 48 insertions(+), 1 deletion(-)
> >> 
> >> Please make sure to add the patch to gnu-system.am.
> >
> > Done.
> >
> >> OK to push with this change.
> >
> > To master or security-updates? 
> >
> > `guix refresh -l grub` reports no dependents other than itself.
> 
> Right, so pushing to ‘master’ is fine.

Pushed as f0150f8724.

> 
> Thanks,
> Ludo’.