keys: CVE-2014-9529

Fixes a race condition flaw in the Linux kernel keys management.
A local attacker could attempt accessing a key while it was being
garbage collected, which would cause the system to crash.

Reference:
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-9529

Upstream fix:
https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/
patch/?id=cf69173f59163182c12e0ecbda52721397468763

Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
Signed-off-by: Paul Vaduva <Paul.Vaduva@enea.com>

2 files changed, 53 insertions, 0 deletions

diff --git a/recipes-kernel/linux/files/keys-CVE-2014-9529-3.14-kernel.patch b/recipes-kernel/linux/files/keys-CVE-2014-9529-3.14-kernel.patch
new file mode 100644
index 0000000..411c66e
--- /dev/null
+++ b/recipes-kernel/linux/files/keys-CVE-2014-9529-3.14-kernel.patch
@@ -0,0 +1,52 @@
+From cf69173f59163182c12e0ecbda52721397468763 Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sasha.levin@oracle.com>
+Date: Mon, 29 Dec 2014 09:39:01 -0500
+Subject: KEYS: close race between key lookup and freeing
+
+commit a3a8784454692dd72e5d5d34dcdab17b4420e74c upstream.
+
+When a key is being garbage collected, it's key->user would get put before
+the ->destroy() callback is called, where the key is removed from it's
+respective tracking structures.
+
+This leaves a key hanging in a semi-invalid state which leaves a window open
+for a different task to try an access key->user. An example is
+find_keyring_by_name() which would dereference key->user for a key that is
+in the process of being garbage collected (where key->user was freed but
+->destroy() wasn't called yet - so it's still present in the linked list).
+
+This would cause either a panic, or corrupt memory.
+
+Fixes CVE-2014-9529.
+Upstream-Status: Backport
+
+Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
+Signed-off-by: David Howells <dhowells@redhat.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
+---
+ security/keys/gc.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/security/keys/gc.c b/security/keys/gc.c
+index d3222b6..009d937 100644
+--- a/security/keys/gc.c
++++ b/security/keys/gc.c
+@@ -157,12 +157,12 @@ static noinline void key_gc_unused_keys(struct list_head *keys)
+                if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
+                        atomic_dec(&key->user->nikeys);
+ 
+-               key_user_put(key->user);
+-
+                /* now throw away the key memory */
+                if (key->type->destroy)
+                        key->type->destroy(key);
+ 
++               key_user_put(key->user);
++
+                kfree(key->description);
+ 
+ #ifdef KEY_DEBUGGING
+-- 
+cgit v0.11.2
+
diff --git a/recipes-kernel/linux/linux-yocto_3.14.bbappend b/recipes-kernel/linux/linux-yocto_3.14.bbappend
index b7933d1..10ea463 100644
--- a/recipes-kernel/linux/linux-yocto_3.14.bbappend
+++ b/recipes-kernel/linux/linux-yocto_3.14.bbappend
@@ -3,6 +3,7 @@ FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
 SRC_URI += "file://HID_CVE_patches/0005-HID-steelseries-validate-output-report-details.patch \
             file://splice-CVE-2014-7822-3.14-kernel.patch \
             file://netfilter-CVE-2014-8160-3.14-kernel.patch \
+            file://keys-CVE-2014-9529-3.14-kernel.patch \
             file://keys-CVE-2015-1333.patch \
             file://udp_fix_behavior_of_wrong_checksums.patch \
             file://net-CVE-2015-2041.patch \