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);
>>
>>