From: Abhishek Pandit-Subedi abhishekpandit@chromium.org
[ Upstream commit 20ae4089d0afeb24e9ceb026b996bfa55c983cc2 ]
Since l2cap_sock_teardown_cb doesn't acquire the channel lock before setting the socket as zapped, it could potentially race with l2cap_sock_release which frees the socket. Thus, wait until the cleanup is complete before marking the socket as zapped.
This race was reproduced on a JBL GO speaker after the remote device rejected L2CAP connection due to resource unavailability.
Here is a dmesg log with debug logs from a repro of this bug: [ 3465.424086] Bluetooth: hci_core.c:hci_acldata_packet() hci0 len 16 handle 0x0003 flags 0x0002 [ 3465.424090] Bluetooth: hci_conn.c:hci_conn_enter_active_mode() hcon 00000000cfedd07d mode 0 [ 3465.424094] Bluetooth: l2cap_core.c:l2cap_recv_acldata() conn 000000007eae8952 len 16 flags 0x2 [ 3465.424098] Bluetooth: l2cap_core.c:l2cap_recv_frame() len 12, cid 0x0001 [ 3465.424102] Bluetooth: l2cap_core.c:l2cap_raw_recv() conn 000000007eae8952 [ 3465.424175] Bluetooth: l2cap_core.c:l2cap_sig_channel() code 0x03 len 8 id 0x0c [ 3465.424180] Bluetooth: l2cap_core.c:l2cap_connect_create_rsp() dcid 0x0045 scid 0x0000 result 0x02 status 0x00 [ 3465.424189] Bluetooth: l2cap_core.c:l2cap_chan_put() chan 000000006acf9bff orig refcnt 4 [ 3465.424196] Bluetooth: l2cap_core.c:l2cap_chan_del() chan 000000006acf9bff, conn 000000007eae8952, err 111, state BT_CONNECT [ 3465.424203] Bluetooth: l2cap_sock.c:l2cap_sock_teardown_cb() chan 000000006acf9bff state BT_CONNECT [ 3465.424221] Bluetooth: l2cap_core.c:l2cap_chan_put() chan 000000006acf9bff orig refcnt 3 [ 3465.424226] Bluetooth: hci_core.h:hci_conn_drop() hcon 00000000cfedd07d orig refcnt 6 [ 3465.424234] BUG: spinlock bad magic on CPU#2, kworker/u17:0/159 [ 3465.425626] Bluetooth: hci_sock.c:hci_sock_sendmsg() sock 000000002bb0cb64 sk 00000000a7964053 [ 3465.430330] lock: 0xffffff804410aac0, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0 [ 3465.430332] Causing a watchdog bite!
Signed-off-by: Abhishek Pandit-Subedi abhishekpandit@chromium.org Reported-by: Balakrishna Godavarthi bgodavar@codeaurora.org Reviewed-by: Manish Mandlik mmandlik@chromium.org Signed-off-by: Marcel Holtmann marcel@holtmann.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/bluetooth/l2cap_sock.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index bbf08c6092f4a..e954fba579f73 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -1340,8 +1340,6 @@ static void l2cap_sock_teardown_cb(struct l2cap_chan *chan, int err)
parent = bt_sk(sk)->parent;
- sock_set_flag(sk, SOCK_ZAPPED); - switch (chan->state) { case BT_OPEN: case BT_BOUND: @@ -1368,8 +1366,11 @@ static void l2cap_sock_teardown_cb(struct l2cap_chan *chan, int err)
break; } - release_sock(sk); + + /* Only zap after cleanup to avoid use after free race */ + sock_set_flag(sk, SOCK_ZAPPED); + }
static void l2cap_sock_state_change_cb(struct l2cap_chan *chan, int state,