Re: [Linux-kernel-mentees] [PATCH net v2] Bluetooth: Fix slab-out-of-bounds read in hci_le_direct_adv_report_evt()

[Marcel Holtmann]

Hi Peilin,

> `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: sta...@vger.kernel.org
> Fixes: 2f010b55884e ("Bluetooth: Add support for handling LE Direct 
> Advertising Report events")
> Reported-and-tested-by: syzbot+24ebd650e20bd263c...@syzkaller.appspotmail.com
> Link: https://syzkaller.appspot.com/bug?extid=24ebd650e20bd263ca01
> Signed-off-by: Peilin Ye <yepeilin...@gmail.com>
> ---
> Change in v2:
>    - add "Cc: stable@" tag.
> 
> net/bluetooth/hci_event.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 4b7fc430793c..aec43ae488d1 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -5863,21 +5863,19 @@ static void hci_le_direct_adv_report_evt(struct 
> hci_dev *hdev,
>                                        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,
>                                  false);
> 
> -             ptr += sizeof(*ev);
> -     }
> -
>       hci_dev_unlock(hdev);
> }

patch has been applied to bluetooth-next tree.

Regards

Marcel