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Bluetooth: Fix l2cap_disconnect_req deadlock

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[ Upstream commit 02c5ea5246a44d6ffde0fddebfc1d56188052976 ]

L2CAP assumes that the locks conn->chan_lock and chan->lock are
acquired in the order conn->chan_lock, chan->lock to avoid
potential deadlock.
For example, l2sock_shutdown acquires these locks in the order:
  mutex_lock(&conn->chan_lock)
  l2cap_chan_lock(chan)

However, l2cap_disconnect_req acquires chan->lock in
l2cap_get_chan_by_scid first and then acquires conn->chan_lock
before calling l2cap_chan_del. This means that these locks are
acquired in unexpected order, which leads to potential deadlock:
  l2cap_chan_lock(c)
  mutex_lock(&conn->chan_lock)

This patch releases chan->lock before acquiring the conn_chan_lock
to avoid the potential deadlock.

Fixes: a2a9339e1c9d ("Bluetooth: L2CAP: Fix use-after-free in l2cap_disconnect_{req,rsp}")
Signed-off-by: Ying Hsu <yinghsu@chromium.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Ying Hsu 2023-05-31 03:44:56 +00:00 committed by Greg Kroah-Hartman
parent 17aac12002
commit 9c7e51b947
1 changed files with 4 additions and 0 deletions
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4
net/bluetooth/l2cap_core.c
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@ -4664,7 +4664,9 @@ static inline int l2cap_disconnect_req(struct l2cap_conn *conn,
chan->ops->set_shutdown(chan);
l2cap_chan_unlock(chan);
mutex_lock(&conn->chan_lock);
l2cap_chan_lock(chan);
l2cap_chan_del(chan, ECONNRESET);
mutex_unlock(&conn->chan_lock);
@ -4703,7 +4705,9 @@ static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn,
return 0;
}
l2cap_chan_unlock(chan);
mutex_lock(&conn->chan_lock);
l2cap_chan_lock(chan);
l2cap_chan_del(chan, 0);
mutex_unlock(&conn->chan_lock);