diff options
| author | Pauli Virtanen <pav@iki.fi> | 2026-08-09 01:06:05 +0300 |
|---|---|---|
| committer | Luiz Augusto von Dentz <luiz.von.dentz@intel.com> | 2026-08-11 15:40:14 -0400 |
| commit | 9db7e5fffbaecfa76aae285bf3e6c8cd4535897c (patch) | |
| tree | f71a9889d00f9ce051fb48aaac68f24fc108f2b4 | |
| parent | d1b752f552896275e639370288ec44e33e6636c6 (diff) | |
| download | linux-next-9db7e5fffbaecfa76aae285bf3e6c8cd4535897c.tar.gz linux-next-9db7e5fffbaecfa76aae285bf3e6c8cd4535897c.zip | |
Bluetooth: L2CAP: reject accept queue add unless BT_LISTEN
New sk should not be added to parent socket accept queue after last
l2cap_sock_cleanup_listen() has run in l2cap_sock_teardown_cb() and
state set to BT_CLOSED, as that can result to UAF on dereferencing the
dangling parent reference.
l2cap_sock_new_connection_cb() may race with parent l2cap_chan teardown,
due to chan->state accessed without consistent locking:
[Task 1] [Task 2]
l2cap_sock_release(parent) l2cap_connect
l2cap_sock_shutdown pchan = l2cap_global_chan_by_psm
l2cap_chan_lock(pchan)
l2cap_chan_close
l2cap_sock_teardown_cb
pchan->state = BT_CLOSED
l2cap_chan_unlock(pchan) ------> l2cap_chan_lock(pchan)
l2cap_new_connection
l2cap_sock_new_connection_cb
l2cap_chan_lock(pchan) <-------- l2cap_chan_unlock(pchan)
l2cap_sock_kill(parent) /* bt_sk(sk)->parent dangling */
Fix by adding check for sk_state == BT_LISTEN after acquiring sk lock in
l2cap_sock_new_connection_cb(). Add lock_sock() around sk_state writes
where missing, to avoid data races.
Although the data races on pchan->state should be fixed too, this
defensive sk_state check probably makes sense in any case.
Fixes: 2ff1a41a912d ("Bluetooth: L2CAP: Fix null-ptr-deref in l2cap_sock_state_change_cb()")
Reported-by: syzbot+9265e754091c2d27ea29@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9265e754091c2d27ea29
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Reported-by: syzbot+9265e754091c2d27ea29@syzkaller.appspotmail.com
Tested-by: syzbot+9265e754091c2d27ea29@syzkaller.appspotmail.com
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
| -rw-r--r-- | net/bluetooth/l2cap_sock.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index cca6201f9cdb..8bf35bc8126f 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -1600,6 +1600,11 @@ static int l2cap_sock_new_connection_cb(struct l2cap_chan *chan, lock_sock(parent); + if (parent->sk_state != BT_LISTEN) { + release_sock(parent); + return -EINVAL; + } + /* Check for backlog size */ if (sk_acceptq_is_full(parent)) { BT_DBG("backlog full %d", parent->sk_ack_backlog); @@ -1763,10 +1768,14 @@ static void l2cap_sock_state_change_cb(struct l2cap_chan *chan, int state, if (!sk) return; + lock_sock(sk); + sk->sk_state = state; if (err) sk->sk_err = err; + + release_sock(sk); } static struct sk_buff *l2cap_sock_alloc_skb_cb(struct l2cap_chan *chan, @@ -1842,6 +1851,8 @@ static void l2cap_sock_resume_cb(struct l2cap_chan *chan) if (!sk) return; + lock_sock(sk); + if (test_and_clear_bit(FLAG_PENDING_SECURITY, &chan->flags)) { sk->sk_state = BT_CONNECTED; chan->state = BT_CONNECTED; @@ -1849,6 +1860,8 @@ static void l2cap_sock_resume_cb(struct l2cap_chan *chan) clear_bit(BT_SK_SUSPEND, &bt_sk(sk)->flags); sk->sk_state_change(sk); + + release_sock(sk); } static void l2cap_sock_set_shutdown_cb(struct l2cap_chan *chan) |