Patch "Documentation/module-signing.txt: Note need for version info if reusing a key" has been added to the 4.7-stable tree

Patch "Documentation/module-signing.txt: Note need for version info if reusing a key" has been added to the 4.7-stable tree

[gregkh]

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

    Documentation/module-signing.txt: Note need for version info if reusing a key

to the 4.7-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:
     documentation-module-signing.txt-note-need-for-version-info-if-reusing-a-key.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From b8612e517c3c9809e1200b72c474dbfd969e5a83 Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben@decadent.org.uk>
Date: Thu, 28 Apr 2016 09:24:05 +0930
Subject: Documentation/module-signing.txt: Note need for version info if reusing a key

From: Ben Hutchings <ben@decadent.org.uk>

commit b8612e517c3c9809e1200b72c474dbfd969e5a83 upstream.

Signing a module should only make it trusted by the specific kernel it
was built for, not anything else.  If a module signing key is used for
multiple ABI-incompatible kernels, the modules need to include enough
version information to distinguish them.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 Documentation/module-signing.txt |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/Documentation/module-signing.txt
+++ b/Documentation/module-signing.txt
@@ -271,3 +271,9 @@ Since the private key is used to sign mo
 the private key to sign modules and compromise the operating system.  The
 private key must be either destroyed or moved to a secure location and not kept
 in the root node of the kernel source tree.
+
+If you use the same private key to sign modules for multiple kernel
+configurations, you must ensure that the module version information is
+sufficient to prevent loading a module into a different kernel.  Either
+set CONFIG_MODVERSIONS=y or ensure that each configuration has a different
+kernel release string by changing EXTRAVERSION or CONFIG_LOCALVERSION.


Patches currently in stable-queue which might be from ben@decadent.org.uk are

queue-4.7/module-invalidate-signatures-on-force-loaded-modules.patch
queue-4.7/documentation-module-signing.txt-note-need-for-version-info-if-reusing-a-key.patch