Hi Cong,
> hci_event_packet() blindly assumes all packets are sane, at least
> for packets allocated via vhci_get_user() path this is not true.
> We have to check if we access skb data out-of-bound with
> pskb_may_pull() before each skb->data dereference on RX path.
>
> Reported-and-tested-by: syzbot+cec7a50c412a2c03f8f5@xxxxxxxxxxxxxxxxxxxxxxxxx
> Reported-and-tested-by: syzbot+660883c56e2fa65d4497@xxxxxxxxxxxxxxxxxxxxxxxxx
> Cc: Marcel Holtmann <marcel@xxxxxxxxxxxx>
> Cc: Johan Hedberg <johan.hedberg@xxxxxxxxx>
> Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Reviewed-by: Tomas Bortoli <tomasbortoli@xxxxxxxxx>
> Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
> ---
> net/bluetooth/hci_event.c | 262 +++++++++++++++++++++++++++++++-------
> 1 file changed, 218 insertions(+), 44 deletions(-)
>
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 609fd6871c5a..2fef70c0bffe 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -2331,10 +2331,13 @@ static void hci_cs_switch_role(struct hci_dev *hdev, u8 status)
>
> static void hci_inquiry_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
> {
> - __u8 status = *((__u8 *) skb->data);
> struct discovery_state *discov = &hdev->discovery;
> struct inquiry_entry *e;
> + __u8 status;
>
> + if (unlikely(!pskb_may_pull(skb, 1)))
> + return;
> + status = *((__u8 *)skb->data);
> BT_DBG("%s status 0x%2.2x", hdev->name, status);
>
> hci_conn_check_pending(hdev);
> @@ -2391,14 +2394,21 @@ static void hci_inquiry_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
> static void hci_inquiry_result_evt(struct hci_dev *hdev, struct sk_buff *skb)
> {
> struct inquiry_data data;
> - struct inquiry_info *info = (void *) (skb->data + 1);
> - int num_rsp = *((__u8 *) skb->data);
> + struct inquiry_info *info;
> + int num_rsp;
>
> BT_DBG("%s num_rsp %d", hdev->name, num_rsp);
>
> + if (unlikely(!pskb_may_pull(skb, 1)))
> + return;
> + num_rsp = *((__u8 *)skb->data);
> if (!num_rsp)
> return;
>
> + if (unlikely(!pskb_may_pull(skb, 1 + num_rsp * sizeof(*info))))
> + return;
> + info = (void *)(skb->data + 1);
> +
> if (hci_dev_test_flag(hdev, HCI_PERIODIC_INQ))
> return;
this really looks like we better create a macro for this. It is repetitive code that can be turned into just a macro usage.
Regards
Marcel
