From e0edf3733fb62f91bbb8ec3fab4a90b0ac2dd037 Mon Sep 17 00:00:00 2001 From: Marcel Holtmann Date: Mon, 20 Feb 2012 14:50:36 +0100 Subject: [PATCH] Bluetooth: Fix issue with shared SKB between HCI raw socket and driver Any HCI raw socket gets a copy of each SKB that is either received or send via the Bluetooth subsystem. The raw socket uses SKB clones to send out data, but the problem is that it needs to add an extra packet type byte in front of it. And some drivers need to also add an extra header before submitting the packet. So far this all worked magically fine since all of the drivers and the raw sockets are adding the same byte at the same location. But that is by pure coincidence. Since the data of cloned SKBs is shared, this means that the raw socket and driver kept writing into the shared data area. To fix this the only safe way is if the HCI raw socket creates a copy of the SKB before sending it out. To not always copy all SKBs around, the copy is only created once and only after any of the HCI filter checks succeeded. Signed-off-by: Marcel Holtmann Signed-off-by: Johan Hedberg --- net/bluetooth/hci_sock.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c index 4dda4574db3e..cf940bd7a2b0 100644 --- a/net/bluetooth/hci_sock.c +++ b/net/bluetooth/hci_sock.c @@ -89,6 +89,7 @@ void hci_send_to_sock(struct hci_dev *hdev, struct sk_buff *skb) { struct sock *sk; struct hlist_node *node; + struct sk_buff *skb_copy = NULL; BT_DBG("hdev %p len %d", hdev, skb->len); @@ -131,18 +132,27 @@ void hci_send_to_sock(struct hci_dev *hdev, struct sk_buff *skb) continue; } - nskb = skb_clone(skb, GFP_ATOMIC); + if (!skb_copy) { + /* Create a private copy with headroom */ + skb_copy = __pskb_copy(skb, 1, GFP_ATOMIC); + if (!skb_copy) + continue; + + /* Put type byte before the data */ + memcpy(skb_push(skb_copy, 1), &bt_cb(skb)->pkt_type, 1); + } + + nskb = skb_clone(skb_copy, GFP_ATOMIC); if (!nskb) continue; - /* Put type byte before the data */ - memcpy(skb_push(nskb, 1), &bt_cb(nskb)->pkt_type, 1); - if (sock_queue_rcv_skb(sk, nskb)) kfree_skb(nskb); } read_unlock(&hci_sk_list.lock); + + kfree_skb(skb_copy); } /* Send frame to control socket */ -- 2.20.1