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| author | Abhishek Pandit-Subedi <abhishekpandit@chromium.org> | 2020-09-11 15:33:18 -0700 |
|---|---|---|
| committer | Marcel Holtmann <marcel@holtmann.org> | 2020-09-13 09:46:00 +0200 |
| commit | 20ae4089d0afeb24e9ceb026b996bfa55c983cc2 (patch) | |
| tree | ae5d4fa3b0d60b7025aea0b48af72ece79e32c0c /net/bluetooth/l2cap_sock.c | |
| parent | d5ea32da878d4572761ca4580631748e398542de (diff) | |
| download | linux-20ae4089d0afeb24e9ceb026b996bfa55c983cc2.tar.gz linux-20ae4089d0afeb24e9ceb026b996bfa55c983cc2.tar.bz2 linux-20ae4089d0afeb24e9ceb026b996bfa55c983cc2.zip | |
Bluetooth: Only mark socket zapped after unlocking
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>
Diffstat (limited to 'net/bluetooth/l2cap_sock.c')
| -rw-r--r-- | net/bluetooth/l2cap_sock.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index e1a3e66b1754..e7cfe28140c3 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -1521,8 +1521,6 @@ 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: @@ -1549,8 +1547,11 @@ 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, |