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authorSasha Levin <sasha.levin@oracle.com>2014-12-29 09:39:01 -0500
committerDavid Howells <dhowells@redhat.com>2015-01-05 15:58:01 +0000
commita3a8784454692dd72e5d5d34dcdab17b4420e74c (patch)
treebe2da54315f410323cc2fca04f63da30cbd2147d
parent693a30b8f19a964087a3762d09fb2e1cbad6b0d4 (diff)
KEYS: close race between key lookup and freeing
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. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com>
-rw-r--r--security/keys/gc.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/security/keys/gc.c b/security/keys/gc.c
index 9609a7f0faea..c7952375ac53 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -148,12 +148,12 @@ 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

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