linux-kernel - Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Write in hci_conn

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Date: Sat, 17 Feb 2024 18:57:42 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+1683f76f1b20b826de67@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Write in hci_conn_drop (2)

On Fri, 16 Feb 2024 18:09:19 -0800
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    2c3b09aac00d Add linux-next specific files for 20240214
> git tree:       linux-next
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16c27a58180000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git  master

--- x/net/bluetooth/sco.c
+++ y/net/bluetooth/sco.c
@@ -297,6 +297,7 @@ static int sco_connect(struct sock *sk)
 		sco_sock_set_timer(sk, sk->sk_sndtimeo);
 	}
 
+	hci_conn_get(hcon);
 	release_sock(sk);
 
 unlock:
@@ -439,12 +440,15 @@ static void __sco_sock_close(struct sock
 	case BT_CONNECTED:
 	case BT_CONFIG:
 		if (sco_pi(sk)->conn->hcon) {
+			struct hci_conn *hcon = sco_pi(sk)->conn->hcon;
+
 			sk->sk_state = BT_DISCONN;
 			sco_sock_set_timer(sk, SCO_DISCONN_TIMEOUT);
 			sco_conn_lock(sco_pi(sk)->conn);
-			hci_conn_drop(sco_pi(sk)->conn->hcon);
 			sco_pi(sk)->conn->hcon = NULL;
 			sco_conn_unlock(sco_pi(sk)->conn);
+
+			hci_conn_put(hcon);
 		} else
 			sco_chan_del(sk, ECONNRESET);
 		break;
--