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

Commit Message

Peilin Ye July 9, 2020, 5:18 a.m. UTC

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: [e-mail]
Signed-off-by: Peilin Ye <[e-mail]>
---
 net/bluetooth/hci_event.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Patch

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))