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    Subject[PATCH 4.14 064/242] Bluetooth: Fix slab-out-of-bounds read in hci_le_direct_adv_report_evt()
    Date
    From: Peilin Ye <yepeilin.cs@gmail.com>

    commit f7e0e8b2f1b0a09b527885babda3e912ba820798 upstream.

    `num_reports` is not being properly checked. A malformed event packet with
    a large `num_reports` number makes hci_le_direct_adv_report_evt() read out
    of bounds. Fix it.

    Cc: stable@vger.kernel.org
    Fixes: 2f010b55884e ("Bluetooth: Add support for handling LE Direct Advertising Report events")
    Reported-and-tested-by: syzbot+24ebd650e20bd263ca01@syzkaller.appspotmail.com
    Link: https://syzkaller.appspot.com/bug?extid=24ebd650e20bd263ca01
    Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
    Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/bluetooth/hci_event.c | 12 +++++-------
    1 file changed, 5 insertions(+), 7 deletions(-)

    --- a/net/bluetooth/hci_event.c
    +++ b/net/bluetooth/hci_event.c
    @@ -5141,20 +5141,18 @@ static void hci_le_direct_adv_report_evt
    struct sk_buff *skb)
    {
    u8 num_reports = skb->data[0];
    - void *ptr = &skb->data[1];
    + struct hci_ev_le_direct_adv_info *ev = (void *)&skb->data[1];

    - hci_dev_lock(hdev);
    + if (!num_reports || skb->len < num_reports * sizeof(*ev) + 1)
    + return;

    - while (num_reports--) {
    - struct hci_ev_le_direct_adv_info *ev = ptr;
    + hci_dev_lock(hdev);

    + for (; num_reports; num_reports--, ev++)
    process_adv_report(hdev, ev->evt_type, &ev->bdaddr,
    ev->bdaddr_type, &ev->direct_addr,
    ev->direct_addr_type, ev->rssi, NULL, 0);

    - ptr += sizeof(*ev);
    - }
    -
    hci_dev_unlock(hdev);
    }


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