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authorAbhishek Pandit-Subedi <abhishekpandit@chromium.org>2020-09-11 15:33:18 -0700
committerMarcel Holtmann <marcel@holtmann.org>2020-09-13 09:46:00 +0200
commit20ae4089d0afeb24e9ceb026b996bfa55c983cc2 (patch)
treeae5d4fa3b0d60b7025aea0b48af72ece79e32c0c /net/bluetooth
parentd5ea32da878d4572761ca4580631748e398542de (diff)
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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')
-rw-r--r--net/bluetooth/l2cap_sock.c7
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,