2 files changed, 48 insertions, 30 deletions

diff --git a/include/linux/key.h b/include/linux/key.h
index 96933b1e5d24..c505f83c9691 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -124,7 +124,10 @@ static inline unsigned long is_key_possessed(const key_ref_t key_ref)
 struct key {
 	atomic_t		usage;		/* number of references */
 	key_serial_t		serial;		/* key serial number */
-	struct rb_node		serial_node;
+	union {
+		struct list_head graveyard_link;
+		struct rb_node	serial_node;
+	};
 	struct key_type		*type;		/* type of key */
 	struct rw_semaphore	sem;		/* change vs change sem */
 	struct key_user		*user;		/* owner of this key */
diff --git a/security/keys/gc.c b/security/keys/gc.c
index a42b45531aac..27610bf72195 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -168,38 +168,45 @@ do_gc:
 }
 
 /*
- * Garbage collect an unreferenced, detached key
+ * Garbage collect a list of unreferenced, detached keys
  */
-static noinline void key_gc_unused_key(struct key *key)
+static noinline void key_gc_unused_keys(struct list_head *keys)
 {
-	key_check(key);
-
-	security_key_free(key);
-
-	/* deal with the user's key tracking and quota */
-	if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
-		spin_lock(&key->user->lock);
-		key->user->qnkeys--;
-		key->user->qnbytes -= key->quotalen;
-		spin_unlock(&key->user->lock);
-	}
+	while (!list_empty(keys)) {
+		struct key *key =
+			list_entry(keys->next, struct key, graveyard_link);
+		list_del(&key->graveyard_link);
+
+		kdebug("- %u", key->serial);
+		key_check(key);
+
+		security_key_free(key);
+
+		/* deal with the user's key tracking and quota */
+		if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
+			spin_lock(&key->user->lock);
+			key->user->qnkeys--;
+			key->user->qnbytes -= key->quotalen;
+			spin_unlock(&key->user->lock);
+		}
 
-	atomic_dec(&key->user->nkeys);
-	if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
-		atomic_dec(&key->user->nikeys);
+		atomic_dec(&key->user->nkeys);
+		if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
+			atomic_dec(&key->user->nikeys);
 
-	key_user_put(key->user);
+		key_user_put(key->user);
 
-	/* now throw away the key memory */
-	if (key->type->destroy)
-		key->type->destroy(key);
+		/* now throw away the key memory */
+		if (key->type->destroy)
+			key->type->destroy(key);
 
-	kfree(key->description);
+		kfree(key->description);
 
 #ifdef KEY_DEBUGGING
-	key->magic = KEY_DEBUG_MAGIC_X;
+		key->magic = KEY_DEBUG_MAGIC_X;
 #endif
-	kmem_cache_free(key_jar, key);
+		kmem_cache_free(key_jar, key);
+	}
 }
 
 /*
@@ -211,6 +218,7 @@ static noinline void key_gc_unused_key(struct key *key)
  */
 static void key_garbage_collector(struct work_struct *work)
 {
+	static LIST_HEAD(graveyard);
 	static u8 gc_state;		/* Internal persistent state */
 #define KEY_GC_REAP_AGAIN	0x01	/* - Need another cycle */
 #define KEY_GC_REAPING_LINKS	0x02	/* - We need to reap links */
@@ -316,15 +324,22 @@ maybe_resched:
 		key_schedule_gc(new_timer);
 	}
 
-	if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2)) {
-		/* Make sure everyone revalidates their keys if we marked a
-		 * bunch as being dead and make sure all keyring ex-payloads
-		 * are destroyed.
+	if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2) ||
+	    !list_empty(&graveyard)) {
+		/* Make sure that all pending keyring payload destructions are
+		 * fulfilled and that people aren't now looking at dead or
+		 * dying keys that they don't have a reference upon or a link
+		 * to.
 		 */
-		kdebug("dead sync");
+		kdebug("gc sync");
 		synchronize_rcu();
 	}
 
+	if (!list_empty(&graveyard)) {
+		kdebug("gc keys");
+		key_gc_unused_keys(&graveyard);
+	}
+
 	if (unlikely(gc_state & (KEY_GC_REAPING_DEAD_1 |
 				 KEY_GC_REAPING_DEAD_2))) {
 		if (!(gc_state & KEY_GC_FOUND_DEAD_KEY)) {
@@ -359,7 +374,7 @@ found_unreferenced_key:
 	rb_erase(&key->serial_node, &key_serial_tree);
 	spin_unlock(&key_serial_lock);
 
-	key_gc_unused_key(key);
+	list_add_tail(&key->graveyard_link, &graveyard);
 	gc_state |= KEY_GC_REAP_AGAIN;
 	goto maybe_resched;