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    Subject[PATCH 5.4 07/22] Bluetooth: L2CAP: Fix calling sk_filter on non-socket based channel
    Date
    From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

    commit f19425641cb2572a33cb074d5e30283720bd4d22 upstream.

    Only sockets will have the chan->data set to an actual sk, channels
    like A2MP would have its own data which would likely cause a crash when
    calling sk_filter, in order to fix this a new callback has been
    introduced so channels can implement their own filtering if necessary.

    Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
    Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    include/net/bluetooth/l2cap.h | 2 ++
    net/bluetooth/l2cap_core.c | 7 ++++---
    net/bluetooth/l2cap_sock.c | 14 ++++++++++++++
    3 files changed, 20 insertions(+), 3 deletions(-)

    --- a/include/net/bluetooth/l2cap.h
    +++ b/include/net/bluetooth/l2cap.h
    @@ -623,6 +623,8 @@ struct l2cap_ops {
    struct sk_buff *(*alloc_skb) (struct l2cap_chan *chan,
    unsigned long hdr_len,
    unsigned long len, int nb);
    + int (*filter) (struct l2cap_chan * chan,
    + struct sk_buff *skb);
    };

    struct l2cap_conn {
    --- a/net/bluetooth/l2cap_core.c
    +++ b/net/bluetooth/l2cap_core.c
    @@ -6701,9 +6701,10 @@ static int l2cap_data_rcv(struct l2cap_c
    goto drop;
    }

    - if ((chan->mode == L2CAP_MODE_ERTM ||
    - chan->mode == L2CAP_MODE_STREAMING) && sk_filter(chan->data, skb))
    - goto drop;
    + if (chan->ops->filter) {
    + if (chan->ops->filter(chan, skb))
    + goto drop;
    + }

    if (!control->sframe) {
    int err;
    --- a/net/bluetooth/l2cap_sock.c
    +++ b/net/bluetooth/l2cap_sock.c
    @@ -1479,6 +1479,19 @@ static void l2cap_sock_suspend_cb(struct
    sk->sk_state_change(sk);
    }

    +static int l2cap_sock_filter(struct l2cap_chan *chan, struct sk_buff *skb)
    +{
    + struct sock *sk = chan->data;
    +
    + switch (chan->mode) {
    + case L2CAP_MODE_ERTM:
    + case L2CAP_MODE_STREAMING:
    + return sk_filter(sk, skb);
    + }
    +
    + return 0;
    +}
    +
    static const struct l2cap_ops l2cap_chan_ops = {
    .name = "L2CAP Socket Interface",
    .new_connection = l2cap_sock_new_connection_cb,
    @@ -1493,6 +1506,7 @@ static const struct l2cap_ops l2cap_chan
    .set_shutdown = l2cap_sock_set_shutdown_cb,
    .get_sndtimeo = l2cap_sock_get_sndtimeo_cb,
    .alloc_skb = l2cap_sock_alloc_skb_cb,
    + .filter = l2cap_sock_filter,
    };

    static void l2cap_sock_destruct(struct sock *sk)

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