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authorYing Hsu <yinghsu@chromium.org>2023-05-31 06:44:56 +0300
committerLuiz Augusto von Dentz <luiz.von.dentz@intel.com>2023-06-06 03:13:14 +0300
commit02c5ea5246a44d6ffde0fddebfc1d56188052976 (patch)
treef738f7a76be161ed2cce14b3b459fbadb50bb984 /net/bluetooth/l2cap_core.c
parent47c5d829a3e326b7395352a10fc8a6effe7afa15 (diff)
downloadlinux-02c5ea5246a44d6ffde0fddebfc1d56188052976.tar.xz
Bluetooth: Fix l2cap_disconnect_req deadlock
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>
Diffstat (limited to 'net/bluetooth/l2cap_core.c')
-rw-r--r--net/bluetooth/l2cap_core.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 376b523c7b26..d9c4d26b2518 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4663,7 +4663,9 @@ 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);
@@ -4702,7 +4704,9 @@ 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);