2020-07-10 16:12:31

by Peilin Ye

Subject: [Linux-kernel-mentees] [PATCH v3] net/bluetooth: Fix slab-out-of-bounds read in hci_extended_inquiry_result_evt()

Check upon `num_rsp` is insufficient. A malformed event packet with a
large `num_rsp` number makes hci_extended_inquiry_result_evt() go out
of bounds. Fix it.

This patch fixes the following syzbot bug:

https://syzkaller.appspot.com/bug?id=4bf11aa05c4ca51ce0df86e500fce486552dc8d2

Reported-by: [email protected]
Cc: [email protected]
Signed-off-by: Peilin Ye <[email protected]>
---
Change in v3:
- Minimum `skb->len` requirement was 1 byte inaccurate since `info`
starts from `skb->data + 1`. Fix it.

Changes in v2:
- Use `skb->len` instead of `skb->truesize` as the length limit.
- Leave `num_rsp` as of type `int`.

net/bluetooth/hci_event.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 03a0759f2fc2..13d8802b8137 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -4375,7 +4375,7 @@ static void hci_extended_inquiry_result_evt(struct hci_dev *hdev,

BT_DBG("%s num_rsp %d", hdev->name, num_rsp);

- if (!num_rsp)
+ if (!num_rsp || skb->len < num_rsp * sizeof(*info) + 1)
return;

if (hci_dev_test_flag(hdev, HCI_PERIODIC_INQ))
--
2.25.1

2020-07-10 17:09:33

by Marcel Holtmann

Subject: Re: [Linux-kernel-mentees] [PATCH v3] net/bluetooth: Fix slab-out-of-bounds read in hci_extended_inquiry_result_evt()

Hi Peilin,

> Check upon `num_rsp` is insufficient. A malformed event packet with a
> large `num_rsp` number makes hci_extended_inquiry_result_evt() go out
> of bounds. Fix it.
>
> This patch fixes the following syzbot bug:
>
> https://syzkaller.appspot.com/bug?id=4bf11aa05c4ca51ce0df86e500fce486552dc8d2
>
> Reported-by: [email protected]
> Cc: [email protected]
> Signed-off-by: Peilin Ye <[email protected]>
> ---
> Change in v3:
> - Minimum `skb->len` requirement was 1 byte inaccurate since `info`
> starts from `skb->data + 1`. Fix it.
>
> Changes in v2:
> - Use `skb->len` instead of `skb->truesize` as the length limit.
> - Leave `num_rsp` as of type `int`.
>
> net/bluetooth/hci_event.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel