[PATCH 4.19 091/346] Bluetooth: Fix slab-out-of-bounds read in hci_le_direct_adv_report_evt()

Greg Kroah-Hartman
2020-12-28T16:08:17Z

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
@@ -5596,21 +5596,19 @@ 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,
false);

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