Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in __timer_delete

[Hillf Danton]

On Wed, 27 Nov 2024 10:59:25 -0800
> syzbot found the following issue on:
> 
> HEAD commit:    2c22dc1ee3a1 Merge tag 'mailbox-v6.13' of git://git.kernel..
> git tree:       upstream
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16143778580000

#syz test

--- x/net/bluetooth/sco.c
+++ y/net/bluetooth/sco.c
@@ -192,7 +192,6 @@ static struct sco_conn *sco_conn_add(str
 			conn->hcon = hcon;
 			sco_conn_unlock(conn);
 		}
-		sco_conn_put(conn);
 		return conn;
 	}
 
@@ -201,6 +200,7 @@ static struct sco_conn *sco_conn_add(str
 		return NULL;
 
 	kref_init(&conn->ref);
+	kref_get(&conn->ref);
 	spin_lock_init(&conn->lock);
 	INIT_DELAYED_WORK(&conn->timeout_work, sco_sock_timeout);
 
--