linux-kernel - [PATCH] bluetooth/hci: disallow setting handle bigger than HCI_CONN_HANDLE

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Date: Thu, 20 Jun 2024 22:27:47 +0300
From: Pavel Skripkin <paskripkin@...il.com>
To: marcel@...tmann.org,
	johan.hedberg@...il.com,
	luiz.dentz@...il.com
Cc: william.xuanziyang@...wei.com,
	linux-bluetooth@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Pavel Skripkin <paskripkin@...il.com>,
	syzbot+b2545b087a01a7319474@...kaller.appspotmail.com
Subject: [PATCH] bluetooth/hci: disallow setting handle bigger than HCI_CONN_HANDLE_MAX

Syzbot hit warning in hci_conn_del() caused by freeing handle that was
not allocated using ida allocator.

This is caused by handle bigger than HCI_CONN_HANDLE_MAX passed by
hci_le_big_sync_established_evt(), which makes code think it's unset
connection.

Add same check for handle upper bound as in hci_conn_set_handle() to
prevent warning.

Fixes: https://syzkaller.appspot.com/bug?extid=b2545b087a01a7319474
Reported-by: syzbot+b2545b087a01a7319474@...kaller.appspotmail.com
Fixes: 181a42edddf5 ("Bluetooth: Make handle of hci_conn be unique")
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
---
 net/bluetooth/hci_conn.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 0c76dcde5361..080053a85b4d 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -899,8 +899,8 @@ static int hci_conn_hash_alloc_unset(struct hci_dev *hdev)
 			       U16_MAX, GFP_ATOMIC);
 }
 
-struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
-			      u8 role, u16 handle)
+static struct hci_conn *__hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
+				       u8 role, u16 handle)
 {
 	struct hci_conn *conn;
 
@@ -1041,7 +1041,16 @@ struct hci_conn *hci_conn_add_unset(struct hci_dev *hdev, int type,
 	if (unlikely(handle < 0))
 		return ERR_PTR(-ECONNREFUSED);
 
-	return hci_conn_add(hdev, type, dst, role, handle);
+	return __hci_conn_add(hdev, type, dst, role, handle);
+}
+
+struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
+			      u8 role, u16 handle)
+{
+	if (handle > HCI_CONN_HANDLE_MAX)
+		return ERR_PTR(-EINVAL);
+
+	return __hci_conn_add(hdev, type, dst, role, handle);
 }
 
 static void hci_conn_cleanup_child(struct hci_conn *conn, u8 reason)
-- 
2.45.2