linux-kernel - [PATCH 5.5 22/23] Bluetooth: Fix race condition in hci_release

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200203161906.839102086@linuxfoundation.org>
Date:   Mon,  3 Feb 2020 16:20:42 +0000
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+eba992608adf3d796bcc@...kaller.appspotmail.com,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Johan Hedberg <johan.hedberg@...el.com>
Subject: [PATCH 5.5 22/23] Bluetooth: Fix race condition in hci_release_sock()

From: Dan Carpenter <dan.carpenter@...cle.com>

commit 11eb85ec42dc8c7a7ec519b90ccf2eeae9409de8 upstream.

Syzbot managed to trigger a use after free "KASAN: use-after-free Write
in hci_sock_bind".  I have reviewed the code manually and one possibly
cause I have found is that we are not holding lock_sock(sk) when we do
the hci_dev_put(hdev) in hci_sock_release().  My theory is that the bind
and the release are racing against each other which results in this use
after free.

Reported-by: syzbot+eba992608adf3d796bcc@...kaller.appspotmail.com
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Johan Hedberg <johan.hedberg@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/bluetooth/hci_sock.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -831,6 +831,8 @@ static int hci_sock_release(struct socke
 	if (!sk)
 		return 0;
 
+	lock_sock(sk);
+
 	switch (hci_pi(sk)->channel) {
 	case HCI_CHANNEL_MONITOR:
 		atomic_dec(&monitor_promisc);
@@ -878,6 +880,7 @@ static int hci_sock_release(struct socke
 	skb_queue_purge(&sk->sk_receive_queue);
 	skb_queue_purge(&sk->sk_write_queue);
 
+	release_sock(sk);
 	sock_put(sk);
 	return 0;
 }