From c4e5bafa661126b7b42459ad32d4c2cc589ef8fb Mon Sep 17 00:00:00 2001 From: Johan Hedberg Date: Thu, 10 Oct 2013 13:33:37 +0200 Subject: [PATCH] Bluetooth: Fix potential double-frees of L2CAP skbs The l2cap_recv_frame function is expected to take ownership and eventually free the skb passed to it. We need to ensure that the conn->rx_skb pointer is no longer reachable when calling l2cap_recv_frame so that no other function, such as l2cap_conn_del, may think that it can free conn->rx_skb. An actual situation when this can happen is when smp_sig_channel (called from l2cap_recv_frame) fails and l2cap_conn_del gets called as a consequence. The l2cap_conn_del function would then try to free conn->rx_skb, but as the same skb was just passed to smp_sig_channel and freed we get a double-free. Signed-off-by: Johan Hedberg Signed-off-by: Marcel Holtmann --- net/bluetooth/l2cap_core.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index a9a7df6639a7..06e7173c2d13 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -6798,9 +6798,13 @@ int l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags) conn->rx_len -= skb->len; if (!conn->rx_len) { - /* Complete frame received */ - l2cap_recv_frame(conn, conn->rx_skb); + /* Complete frame received. l2cap_recv_frame + * takes ownership of the skb so set the global + * rx_skb pointer to NULL first. + */ + struct sk_buff *rx_skb = conn->rx_skb; conn->rx_skb = NULL; + l2cap_recv_frame(conn, rx_skb); } break; } -- 2.20.1