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Date:   Fri, 24 Nov 2023 03:29:23 -0800
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Subject: Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in __lock_sock
From:   syzbot <syzbot+60bfed6b415fbd1fbb87@syzkaller.appspotmail.com>
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Subject: [bluetooth?] KASAN: slab-use-after-free Read in __lock_sock
Author: eadavis@qq.com

please test uaf in __lock_sock

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git 8de1e7afcc1c

diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index c736186aba26..062ab9926146 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -270,6 +270,7 @@ static int sco_connect(struct sock *sk)
 		goto unlock;
 	}
 
+	hci_conn_get(hcon);
 	conn = sco_conn_add(hcon);
 	if (!conn) {
 		hci_conn_drop(hcon);
@@ -300,7 +301,8 @@ static int sco_connect(struct sock *sk)
 
 unlock:
 	hci_dev_unlock(hdev);
-	hci_dev_put(hdev);
+	if (err)
+		hci_dev_put(hdev);
 	return err;
 }
 
@@ -438,12 +440,13 @@ static void __sco_sock_close(struct sock *sk)
 	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;