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

Peilin Ye
2020-07-09T05:20:05Z

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. Also, make `num_rsp` unsigned.

This patch fixes the following syzbot bug:

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

Reported-by: syzbot+d8489a79b781849b9c46@syzkaller.appspotmail.com
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
---
net/bluetooth/hci_event.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 03a0759f2fc2..29aff5e7dec2 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -4369,13 +4369,13 @@ static void hci_extended_inquiry_result_evt(struct hci_dev *hdev,
struct sk_buff *skb)
{
struct inquiry_data data;
- struct extended_inquiry_info *info = (void *) (skb->data + 1);
- int num_rsp = *((__u8 *) skb->data);
+ struct extended_inquiry_info *info = (void *)(skb->data + 1);
+ __u8 num_rsp = *((__u8 *)skb->data);
size_t eir_len;

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

- if (!num_rsp)
+ if (!num_rsp || num_rsp * sizeof(*info) > skb->truesize)
return;

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