Bluetooth: stop proccessing malicious adv data

[ Upstream commit 3a56ef719f0b9682afb8a86d64b2399e36faa4e6 ]

Syzbot reported slab-out-of-bounds read in hci_le_adv_report_evt(). The
problem was in missing validaion check.

We should check if data is not malicious and we can read next data block.
If we won't check ptr validness, code can read a way beyond skb->end and
it can cause problems, of course.

Fixes: e95beb414168 ("Bluetooth: hci_le_adv_report_evt code refactoring")
Reported-and-tested-by: syzbot+e3fcb9c4f3c2a931dc40@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 9f52145bb7b7639e5c221778188126f8143ef870..7ffcca9ae82a122731169a0b26e55f9c61aea810 100644 (file)
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -5661,7 +5661,8 @@ static void hci_le_adv_report_evt(struct hci_dev *hdev, struct sk_buff *skb)
                struct hci_ev_le_advertising_info *ev = ptr;
                s8 rssi;
 
-               if (ev->length <= HCI_MAX_AD_LENGTH) {
+               if (ev->length <= HCI_MAX_AD_LENGTH &&
+                   ev->data + ev->length <= skb_tail_pointer(skb)) {
                        rssi = ev->data[ev->length];
                        process_adv_report(hdev, ev->evt_type, &ev->bdaddr,
                                           ev->bdaddr_type, NULL, 0, rssi,
@@ -5671,6 +5672,11 @@ static void hci_le_adv_report_evt(struct hci_dev *hdev, struct sk_buff *skb)
                }
 
                ptr += sizeof(*ev) + ev->length + 1;
+
+               if (ptr > (void *) skb_tail_pointer(skb) - sizeof(*ev)) {
+                       bt_dev_err(hdev, "Malicious advertising data. Stopping processing");
+                       break;
+               }
        }
 
        hci_dev_unlock(hdev);