On 30/8/21 8:15 am, Hillf Danton wrote:
On Mon, 30 Aug 2021 02:34:11 +0800 Desmond Cheong Zhi Xi wrote:
Ok I went back to make a more thorough audit. Even without calling
cancel_delayed_work_sync, sco_sock_timeout should not cause a UAF.
I believe the real issue is that we can allocate a connection twice in
sco_connect. This means that the first connection gets lost and we're
unable to clean it up properly.
Thoughts on this?
LGTM regardless of the uaf reported.
Hillf
Thanks for taking a look. It passed the Syzbot reproducer too, so I
think the root cause should have been addressed.
I'll write up a patch to summarize what we found out. May I include you
as a Co-developed-by: author?
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git e3f30ab28ac8
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -578,9 +578,6 @@ static int sco_sock_connect(struct socket *sock, struct sockaddr *addr, int alen
addr->sa_family != AF_BLUETOOTH)
return -EINVAL;
- if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND)
- return -EBADFD;
-
if (sk->sk_type != SOCK_SEQPACKET)
return -EINVAL;
@@ -591,6 +588,13 @@ static int sco_sock_connect(struct socket *sock, struct sockaddr *addr, int alen
lock_sock(sk);
+ if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) {
+ hci_dev_unlock(hdev);
+ hci_dev_put(hdev);
+ err = -EBADFD;
+ goto done;
+ }
+
/* Set destination address and psm */
bacpy(&sco_pi(sk)->dst, &sa->sco_bdaddr);
