2020-11-09 12:17:34

by Marcel Holtmann

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

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: [email protected]
> Fixes: 2f010b55884e ("Bluetooth: Add support for handling LE Direct Advertising Report events")
> Reported-and-tested-by: [email protected]
> Link: https://syzkaller.appspot.com/bug?extid=24ebd650e20bd263ca01
> Signed-off-by: Peilin Ye <[email protected]>
> ---
> 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

2020-11-11 05:19:34

by Peilin Ye

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

On Mon, Nov 09, 2020 at 01:16:53PM +0100, Marcel Holtmann wrote:
> 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: [email protected]
> > Fixes: 2f010b55884e ("Bluetooth: Add support for handling LE Direct Advertising Report events")
> > Reported-and-tested-by: [email protected]
> > Link: https://syzkaller.appspot.com/bug?extid=24ebd650e20bd263ca01
> > Signed-off-by: Peilin Ye <[email protected]>
> > ---
> > 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.

Thank you for reviewing it,

Peilin Ye